Thank you home hydro for the timely and most helpful reply. I see how this works with the ground source heat pump but I cannot see how it would cool 300 gallons of solution. Found an old website of NC State that gave volume per 100 feet of pipe. The smallest pipe size they had was 1 inch pvc which holds 4.7 gallons per 100 feet. With the half inch drip irrigation tubing the volume would be much less.Even if one were to run a thousand feet seems it would be such a low volume of cold water returning to the res it would not amount to much. Thoughts, anyone?willyt

I'm not really understanding I guess. Are you wanting to know how much tubing you would need to hold 300 gallons of nutrient solution? Or are you thinking that the volume of water inside the tubing needs to be equal to the size of the reservoir to be effective. As in your example if you used 1 inch tubing and it only held 4.7 gallons for 100 feet you would need 6300 feet of tubing. If so I think you are looking at it all wrong.

It's not about how much water the tubing can hold, it's about how much water you can pump through it (gallons per hour). If your pump can pump 300 gallons of water per hour through the tubing, then you will be able to circulate the entire 300 gallon reservoir every hour. As an example I have a fountain pump that can pump between 300 and 500 gallons per hour at a 1 foot head height (depending on how I have the flow adjuster set). Now considering the trench is say 4 feet deep, and depending on how high above ground level the reservoir is, I would be looking at at least a 4 foot rise (head height). At a 6 foot head height it can pump up to 191 gallons per hour through the tubing (with the flow adjuster wide open). That's a little more than half of 300 gallons. That will circulate the entire volume of water (300 gallons) in the reservoir through the tubing every 2 hours.

It will be able to pump that volume of water through the tubing weather it's 10 feet long or 1000 feet long. So again it is how much you can pump through it, not how much it can hold. The difference in length, only affects the amount of time the water is inside the tubing. The longer the tube, the more time it has to cool down. A 1000 foot long tube will have 10 times longer to cool down than a 100 foot long tube. That's why longer is better, not because it holds 10 times more water. That's also why a 1/2 inch wide tube will cool down faster than a 1 inch wide tube. There is less volume of liquid to be cooled, therefore it cools down faster.

The only consequence of how much water the tube length holds, is just how much more nutrient solution you need to add to the reservoir. Again going by your example, if 100 feet of 1 inch (inside diameter) tubing holds 4.7 gallons, then 100 feet of 1/2 inch (inside diameter) tubing should hold 1/2 that. Half of 4.7= 2.35. 10 x 2.35 =23.5 gallons. So basically 1000 feet of 1/2 inch tubing holds almost 25 gallons. So instead of a 300 gallon reservoir, you now have a 325 gallon reservoir.

Even if you have a pump that has an outlet line larger than 1/2 inch, you can still use the pump at full capacity by using an inline "Y" connector. Say the pump has a 1 inch outlet. You can use a length of 1 inch tubing to get the full flow the pump can put out, then attach a reducing "Y" connector to split the 1 inch line into 2, 1/2 inch lines. The 1/2 inch lines will cool down quicker, but by spiting the line in two, you still get the full volume of water flow the pump can provide. And by using a "Y" connector instead of a "T" connector, that reduces any flow restriction that the 45 degree turn of the "T" connector would have.

The heat transfer will depend on the surface area of tube in contact with the soil and the temperature differential.

The tube wall thickness and material will have an inherent insulation value that will reduce the rate of heat transfer.

The soil in contact with the tubing will heat up (relatively speaking),which in turn reduces the temperature differential and ultmately slows the heat transfer.

The moisture content and type of soil dictates how rapidly the heat will travel away from the tube.

Thats just a few of the variables :)

Agreed 100% and well put, hex2006 - and my exact train of thoughts and equation.

Thus, a 1.5'" Tube with just enough wall thickness is probably a good compromise regarding practicability, price, effort and trench wide (if for example digging out a trench of around 1-1,5 foot for 2 tubes including return).

On the other hand, digging a 400 long- and 4' deep trench isn't exactly a one man's week-end snap! ;-)

I have recently brought a 2000+ Liter (around 530 gallon) underground reservoir on stream. Supply lines (also underground) are 1" and the main return tube is 2" (while 1.5" when split to any unit). With this solution, the combination of the actual return line plus the 5' plus deep underground reservoir do the trick. Works like a charm and keeps nutrients the few degrees cooler that are needed. And that's exactly what it needs (regardless of any real Thermodynamics in vigor or anybodies anecdotical speculations) - just those few degrees less is all you need! Btw: the units that are connected to this system can alternatively be run as RDWC, Drip or E&F with a slight modification and within a minute job.

Cheers to all,
Jean-Luc

Hi Jean-Luc,
Aye, it all seems very straightforward on the face of it but in reality its far from it.
Here`s a few more spanners to throw into the machine :)

The flow in the center of the tube will be different to the flow at the wall. Smaller tube diameters have less surface area and higher presure loss (bigger pump more energy)
To transfer heat more efficiently you need turbulent flow, corrugated pipe will help there but has a downside.. even more loss.

Do all the math before picking up the spade, the investment in time, effort and cost may not be worth the return :)

Along with the problem of pressure loss with the large tubing, thus larger pump. The wall thickness of large tubing (depending on the actual tubing used) very likely wont actually be any thinner than the 1/2 inch irrigation tubing. Not to mention much higher cost for larger tubing.

Over all, the Smaller tubing will be much more efficient in cooling than larger tubing will. Your just trying to cool a few hundred gallons of nutrient solution, not trying to use it to air condition a house or building. Therefor you don't need the high volumes of water, and the heat exchange unit's that are typical, and necessary in commercial applications. The coils are your heat exchange unit.

By using the smaller 1/2 inch tubing, and a much longer tube, you get much better overall heat transfer within the tube. Simply because there's less volume of water in any given section of a smaller tube, and there's also more water that's actually in direct contact with the tube itself at any given time (thus able to cool down faster). And by having a longer tube, there's more surface area of tubing in contact with both the water inside the tube, and the ground outside the tube. Thus much faster cooling. Again make sure that when you back fill the trench, to fill it about 8-12 inches, then flood the trench with a few inches of water to take out the air pockets between the tube and ground. That way all of the surface of the tubing is in close contact with the soil (for good heat transfer).

Also a trench 1 to 1 1/2 feet deep wont do much. It will protect the tubing from Sunlight. But isn't deep enough for much temperature differential as hex mentions. Commercial instillation's typically go about 6 feet deep. I wouldn't want it to be at less than 3 feet deep myself. That's just about where the ground begins to actually feel cool, and a worth while temperature differential (here anyway). But I would try for 4 feet deep.

And I agree a 400 foot trench is quite a bit for someone on a weekend (even in a week), but quite a bit unnecessary also. First you can probably easily get by with a 50 or 60 foot trench, 4-5 feet deep in order to install a good 700-1000 feet of 1/2 inch tubing. Remember the tubing is going to be stretched out coils, and not tubing completely stretched out in a straight line. Further more, by going down an extra foot, you can get a second (possibly even three) layer/s of stretched out coils in the same trench. Simply by packing the first layer in, and filling the trench with a foot of soil, then laying another layer down (and so on).

Also I wouldn't even want to dig a 10 foot long trench, but that's why they have equipment rental places. Here you can rent a back hoe for about $60 an hour. With any luck you can probably have the entire trench dug in an hour. You can then either back fill it by hand, or set it up to have them come back another day, after you install the tubing to finish back-filling it. To make the job go faster and save money (as well as just a precaution), have the city come in and mark out your underground water, sewer, gas and electrical (power) lines. Yes electrical lines can also be underground, ours is. And unfortunately it's in a place my mom wants to put a shed, and I cant cover that area with a cement base for the shed, in case they ever need to get to it. The city will come out and mark them all for you for free, you just need to call them and set up the appointment's.

That will tell you exactly where you can place the trench, as well as saves a lot time when they come to dig it. Keep in mind also, the trench doesn't even need to be straight, curved trenches, and with corners work just fine.

Hi hex2006,
As you say: "it all seems very straightforward on the face of it but in reality its far from it."

The most common mistake in reasoning consists in confusing the thermodynamics of an active energy producing, "unlimited" and quickly transferring heat/cool exchange source (like, fire, sun, atmospheric heat or cold as well as any artificial heat/cold source or atmospheric heat or cold) with an actual buffer like the underground soil as "earth-source" is.

There is no energy (heat or cold) produced in soil but only buffered and also exchanged relatively slowly from the surrounding area(s). Unlike with any actively energy producing environment and source, (atmospheric air-cooler, etc.) pressure and flow rate (for quicker transfer) are secondary. The surrounding soil of any underground tube only has a certain exchange capacity, which on top of it has a limited heat/cold exchange rate with the surrounding area (as you pointed out with mentioning soil type and moisture content). Anything you think of but doesn't consider the LIMITED exchange rate and c.a.p.a.c.i.t.y of soil is indeed Love's Labour's Lost ;-)

Btw: @hex2006, not sure if amount of turbulent flow matters regarding efficiency here either. As we deal with a slow transfer/exchange rate, the amount of turbulence may not actually count that much. In any active system of the sort, there is always some turbulence. Probably enough of it for an even heat/cool exchange from the transfer rate we can expect.

Quote hex2006: "Do all the math before picking up the spade" Agreed, - or alternatively do small scale testing with your proper climate and conditions, - or copy a working and established model under similar conditions. AND DO NOT RELY ON ANY FORUM DEBATE! LOL

A few more hints: 1. you may lay out your tubing in an area you can irrigate to improve heat exchange through moisture/evaporation (obviously more appropriate with a less deeper laid out system and rather futile from 2' and deeper) 2. if filling trenches or leveling an area you may consider using (mixing in) material that improves heat/cold exchange and evaporation around the tubing. 3. If possible, consider to include (as I did) your actual supply and return lines into the cooling circuit. Depending on kind and size of setup, you indeed may be able to kill two birds with one stone here! 4. If using smaller tubing, pressure is indeed higher through out the system, but pressure equals resistance and friction and in fact a considerable loss in flow rate and thus only less pump performance at the end of the equation.

As home hydro said, i don`t think its worth the effort if you only need to cool a smallish res. It would be cheaper better off insulating the hell out of it and use drain to waste :)
Cooling the res is only effective if the water doesn`t heat up again en route to where its needed and if the rootzone can be kept cool enough for it to make a difference when it arrives.
Mother Nature always has the best plan.. grow roots in an almost infinite amount of mass (soil) which is thermally very stable lol

I haven't relayed on any complicated and labour intensive tubing system anyway, but have holed in my 2000 Liter reservoir 6 feet under ;-)
Which I believe is playing safe by the book, literally.... LOL

Also, happy hydro's 300 gallon venture looks more like medium scale to me.

Mother nature, - speaking of which!? Have you ever seen any sort of insulation of the sort in nature? I haven't and I haven't seen any use of sophisticated insulation in any pro nor commercial system of any size either. And I've been around quite a bit (although there may be exceptions I am not aware of) .
I am not fund of any sophisticated insulation based cooling system with hydro anyway, except a styrofoam cover or other simple and quite obvious measures. But it stops about there. It really is the same deal with thermodynamics here as well - it seems obvious to insulate but in most cases it is much more complicated than it seems. With insulation you mainly delay, you do not cool nor heat anything. Insulation makes merely sense if there is heat or cold provided from an extra (artificial) source like in a fridge or an air conditioned or heated home - otherwise it (especially in this very context) not only delays heating up but in the meantime the natural cooling down process is delayed as well. In fact insulation hinders cooling down through heat dispersion and evaporation. ;-)

"There is no energy (heat or cold) produced in soil"

Of coarse not, and I don't remember anyone suggesting anything of the sort. The heat is produced above ground, the heat is then transferred into the large mass of soil called earth. I thought I left enough links explaining the principals behind Geothermal energy that I wouldn't need to completely explain, but I will just for jean-luc. Nobody was confused here about the what geothermal energy is (that I can see). But I'll explain it for you anyway luches.

The principal is simple, the earth underground remains at a constant temperature thought the year, both summer and winter (when deep enough). This underground temperature does somewhat vary from one region to another, and for the given depth, but still remains constant (the deeper the more constant). During summer months you can pump a liquid through a underground tube, and there's a exchange of temperatures between the two (the earth, and the tube). Each maternal has a different conductivity to it, and will affect the rate of exchange between what's in the tube, and the ground. Even any tiny air bubbles between the tube and soil will effect the rate of heat exchange, as well as the diameter of the tube, and the volume of liquid in the tube will affect the heat exchange rate. As well as the ground water content, there are many variables that affect the the rate of heat exchange.

The heat in the tube is sucked out into the ground (earth), simply because it's cooler than the tube. That"s a law of physics (at least on this continent it is). In in doing so it warms up the ground that it's running thorough (as the word exchange in heat exchange suggests). The exchange of heat between one material and another "IS" a form of energy, that is why it's called Geothermal energy (hopefully I don't need to explain the word Geothermal).

Geothermal energy is considered an unlimited source of energy because it's continually being renewed by the large mass we call planet earth. As the surrounding area of soil the tube is running through warms up (because of the exchange of heat from the tube), it's continually being pulled farther away from the tube. This happens because of the same principal that pulls it out of the tube in the first place. That's that cold attracts heat (pulling heat into it), so anything warm will loose its heat to something colder until they wind up being equal temperatures. The larger the temperature differential is, the faster the heat is pulled out into the cold mass (called earth).

This type of system is also useful during winter months. During winter months, the underground temperature is warmer than the above ground temperatures. The principal of heat exchange remains the same, cold always sucks in heat. The water in the tube is colder than the ground, so the tube sucks in the earths heat, warming up the water in the tube.

Some areas have permafrost and you need it to be deep enough, or the tubing will burst from freezing. Just like the system for summer months where it needs to be deep enough to reach cool earth, you need to be deep enough to reach warm earth during winter. If just 2 feet was good enough then there wouldn't be such a thing as permafrost. And no luches it's not just because the water in the dirt froze, there is more water farther underground than there is on top, and that isn't frozen. That water has more insulation from the above ground temperatures, and that ground insulation works during summer also.

How deep top dig the trench is pretty self explanatory to us normal people. Any kid knows that the soil in a 6 foot deep hole would be cooler than in a 2 foot hole. Any kid who has dug a hole, and what kid hasn't. Nothing so difficult to understand there.

"Unlike with any actively energy producing environment and source, (atmospheric air-cooler, etc.) pressure and flow rate (for quicker transfer) are secondary."

Again, nobody has said that geothermal energy is a atmospheric air-cooler. The heat exchange unit on commercial systems converts the water temperature into a source of atmospheric air conditioning (and/or heating), and like I said that's not necessary in this application. He's not trying to heat his house. In this case cooling the water is the goal. Also in this case the water pressure in the tube is needed to circulate enough water to keep the 300 gallons cool. If the 300 gallons heats up faster than he can replace it with cool water, it wouldn't work for the purpose.

And if you think a faster flow rate is for quicker transfer of heat between the tube and ground, you are way off the mark. The quicker the water flows through the tube, the less time it has to cool down. Thus the complete opposite, that's the point of the tube being longer. Allowing the water to have more time (to cool) inside the tube before it exits the tube. Hex wasn't referring to a faster flow rate in a larger tube helping it cool because it's faster. When the water is moving around faster, it churns up (mixes) the water inside the tube more. Therefore each water molecule has more chance to be near the tube walls, where it has more chance to exchange heat. With larger tubing that's much more of an issue because the water in the center of a larger tube is farther away from the tube walls. The corrugated tubing was to help churn up the water within the tube itself, mixing it up.

"1. you may lay out your tubing in an area you can irrigate to improve heat exchange through moisture/evaporation (obviously more appropriate with a less deeper laid out system and rather futile from 2' and deeper)"

Quite pointless actually, not to mention a big waist of water. A deep enough trench wont need to be watered to accelerate heat exchange. A deeper trench will be cooler to start with, and will also have enough ground water to keep good heat exchange going. Being lazy and not going deep enough in the first place just doesn't pay.

"material that improves heat/cold exchange and evaporation around the tubing"
If you think moisture evaporation is what makes geothermal energy work, again your just way off the mark and need to re think the whole theory. Evaporation has nothing at all to do with it. Geothermal energy doesn't work like an evaporative cooler (swamp cooler).

"but pressure equals resistance and friction and in fact a considerable loss in flow rate"

This doesn't even make sense. I get pressure and resistance, as well as friction. But there is no way that an increase in pressure equals less flow. The household water pressure is about 60 PSI. Do you think for a minute if you doped the water pressure to 30 PSI, you would wind up with a higher flow rate??? I pity the fool that does.

"but have holed in my 2000 Liter reservoir 6 feet under ;-)Which I believe is playing safe by the book, literally.... LOL""

At least here is some common sense. Why not just two feet as you so animatedly state is all that's necessary. Simple because it is a lot cooler 6 feet deep than it's 2 feet deep. Dahhhhh.

"Mother nature, - speaking of which!? Have you ever seen any sort of insulation of the sort in nature?

Yes, mother nature keeps the roots insulated from above ground temps, and cool by insulating them in the earth (soil). Mother nature isn't taking the plants roots out of the ground, and placing them in buckets above ground. That's done by humans.

"I haven't and I haven't seen any use of sophisticated insulation in any pro nor commercial system of any size either"

It's funny that the concept of insulation is a sophisticated concept and/or process to you. To most of us it's real simple. In fact they make something called pipe insulation for the specific purpose of insulating tubes (called pipes). Get this, they even make them to fit the size tubing you have, isn't that amazing? In the home insulation department at the hardware store they have sheets of something called Styrofoam insulation. It even comes in different thicknesses. It's a real sophisticated and time consuming process to cut to size though. I use a soldering iron I got at radio shack for whopping 3 or 4 bucks to cut through it like butter (real sophisticated stuff ha). Setting the buckets on top of a piece of Styrofoam is real sophisticated (to some I guess). Or is wrapping a layer or two of thin flexible foam insulation around a bucket the sophisticated part. You obviously don't think that insulating the reservoir is sophisticated or not useful, or you wouldn't have put yours 6 feet deep.

Most large PRO setups use an in ground reservoir (back to geothermal energy again), and/or the reservoir is inside the climate controlled greenhouse. Gee I wonder why.

"With insulation you mainly delay, you do not cool nor heat anything. Insulation makes merely sense if there is heat or cold provided from an extra (artificial) source like in a fridge or an air conditioned or heated home"

Well no Daaaaaa. That's the point. When you go to the trouble of creating a geothermal energy trench to cool your nutrient solution, you want to keep the cool temp in your root zone, rather than radiating out. You don't want it to just heat up in the above ground part of the system, or your just either defeating the purpose, or needing to use a lot more resources to achieve the same result. The coiled tubing in the geothermal trench is the cooling source. Get up to speed.

Depending on the exact local prices. A very efficient geothermal energy trench can be built. Prices for me here would be about like this. $60 to dig the trench, $50 or so for a pump, $45 for 700 feet of 1/2 inch tubing, $5 or so for a few PVC connectors to connect the tube to the pump tube and an overflow back to the reservoir. Including tax it would be around $200. And If I wanted for another $45 I could double the amount of cooling coils (tubing), to 1400 feet (although it will take a little longer to dig a longer trench, it can be split in to two near by trenches).. Also if you wanted to eliminate the need for a second pump, you can run the coils in-line with the feed to the plants, though it will only be able to cool the reservoir while the pump is running, although depending on the setup and design that may be just fine. As long as the trench was deep enough, and assuming that the reservoir was at least partially in the ground. A setup like this would probably be able to expand the amount of plants being grown to three times what's planed or more. Especially considering the larger the reservoir, the slower it will heat up.

Heat being sucked from the tube implies a high transfer rate but the primary mode will be conduction and possibly radiation if the soil is fairly open. Soil moisture content is by far the most important variable as wet soil will wick energy away from the tube at a much faster rate than dry soil, maintaining a higher temperature differential.

High liquid flowrate through the tubing is more efficient as it also maintains a higher differential along the full length of the tubing. Dropping a large volume of water by 1 degree per circuit is more efficient than dropping a very small amount by 10 degrees by using a lower flowrate.

I have experience of the difference flow rate makes to the efficiency albeit with a different media. I use the soilmass below my greenhouse to cool air and store excess energy, 84F air in will exit at 55F at 700cfm, the air spends less than half a second underground. Slower fan speed provides a lower exit temperature but transfers a lot less energy due to the low efficiency. On a good day i get a COP of 30.

"Geothermal energy is considered an unlimited source of energy because it's continually being renewed by the large mass we call planet earth"
Off topic, however, I like to open eyes to the concept at times but. . does anybody know of any researarch that's been conducted on how much energy we (as in the whole human race) could siphon off of the earths core before we extract enough that the core begins to cool down and we create another Mars. On a small scale, such as what's being discussed here, you could consider it an unlimited supply. But globally, as a source of energy for the world, it is far from infinite. Just as collecting too much of the suns radiation could have detrimental effects, or too many fans (i.e. wind mills) could slow down the worlds air currents, these things should be researched before we go whole hog on renewable energy.
I will step off my soap box now.

Ya grizz,
everything has a cause and effect, and I have thought about that a time or two. Just like using solar energy, it isn't exactly without it's cost to the environment either. After all it takes energy and resources to build the solar panels and all the parts necessary. Including the battery banks to store the electricity (in off the grid systems). I often wonder if the toll on the environment, as well as all energy expended on creating, and distribution of all the materials and parts necessary for solar energy is any better than just using the sources of electricity that are in place already from a carbon footprint standpoint. Basically carbon footprint to build and maintain solar systems per kilowatt VS the carbon footprint per kilowatt for traditional coal, nuclear, dam power ETC..

As for using geothermal and heating up the earths core, I don't know of any study's that are taking a look at the long term (50 years+) effects of using geothermal on a large scale. Personalty I think it would be about 100 years before such a study would have any real accuracy even so. Simply because of the shear mass of the earth, and the very little use of geothermal in comparison. As well as the fact that two thirds of the earths surface is covered by water, therefor not assessable for much Geothermal use (though I suppose someday they could drill for it much the same way they do for oil). Also don't forget that the earths cor is molten lava (theirs not to much that's hotter than that), and has been for billions of years. I don't think anything humanity will ever do, will be able inject enough heat into the earth that could compare to what's already there.

hex2006
You use Geothermal for air conditioning, simply by running air through underground tubing? That's a concept that I have briefly thought about, but never really actually considered. I would love to hear about all the particular, both in design, and efficiency. It would be great if you could start a thread about it. That sounds like something that would really be useful for me.

I live in the desert, and it gets extremely hot during summer. Shoot, today and tomorrow is already expected to reach 90 degrees. So it would take a huge electric bill to run an air conditioner to cool a greenhouse. My only option up till now is building an evaporative cooler, but that also requires the greenhouse to be wide open. Basically just using shade cloth and allowing the heat in, or the humidity would reach extreme levels.

Ouch! That did hurt!
Well I've been wrong before (who hasn't) but here I have to officially admit that I was simply wrong about several points. Not actually used to that - and it feels quite a bit funny. ;-)

But then again, I am a bit relieved also that I am not reacting in a mean nor a defensive way. Why won't I? Maybe because I haven't been wrong about everything and right about the main thing at the end. But mostly because thanks to the hard work of the past weeks my latest system is already up and running. As I explained earlier (briefly), it's based on an underground reservoir, massive but not bombastically build from small clay bricks and concrete - of 2000 plus liter reservoir. Six feet under, well that's as deep as we could dig by hand years back, when it was build for it's initial purpose. Yes it was an existing structure but anyway, 2000 liter represent a comfortable buffer for nutrients, pH and temperature. Also, the return lines are 2" wide and laid out deep enough underground to keep the working temperature and perhaps cooling things down even a bit (depending upon climate). I have chosen a 120 watt pump and it draws the nutrients from 1 meter deep only for now. That's pretty much it but the temperatures remain under 27degree C at all times, up to external temps of 35 degree C until now. Up to 28degree C is is what I consider a good result in tropical climate and still safe (from experience of the past years) That's all I wanted to achieve. I am eager to measure the temperatures in a months or so, when we will have up to 42degree C for short periods.

Anyone interested in other details, do not hesitate to ask. Anyone mainly interested in being even more mean with a man who has become too old to die young and has nothing to prove except to himself - please do not even bother nor count on my participation. I am definitely done with some beatnik poseurs around here and elsewhere. Also, you guys go on looking up your links and refine your theories or rewrite other's books. I am merely interested in real scale and practical applications and of course sharing my work and actual experience of the past two decades.

Cheers to all,
Jean-Luc

I've sometimes been a dick in the past I know that myself - but I've never made anything up nor have I given any misinformation intentionally. And I have always delivered. No I'm not getting defensive here at the end, but want as usual deliver proof of what I have described - as I know the watch dogs inside out too, - since. ;-)

Some pics of the described reservoir for illustration purposes:

No copyright on it, because who ever wants to recreate it - they are most welcome;-)

For the heck of it I decided to do a little experiment to see how much water the 1/2 tubing will hold. Because I didn't want to cut my PVC tubing to do it, I started with a 4 foot long (48 inches) 1/2 inch (inside diameter) piece that was already cut. I caped one end, and filled it all the way up. Then poured it into a measuring flask. I expected to need to do a lot more math, but it came out to 8 fluid ounces exactly. So here's what I concluded.

4 feet 1/2 inch tubing = 8oz (1 cup)
x100= 100 cups (400 feet), 16 cups to a gallon= 6.25 gallons
divide by 4= 1.5625 gallons per 100 feet of 1/2 inch (inside diameter) tubing
x10 = 15.625 gallons in 1000 feet of 1/2 inch tubing

This info would be useful for anyone with such a trench system when it comes to a nutrient solution change. Because once you flush the system with fresh water, there will still be water in it (unless you flush the tubing with compressed air). So you would need to account for 15-16 extra gallons of water still in the system (tubing) when mixing the fresh nutrients.

HH, Here`s an example of the heat transfer based on your numbers. Assuming the od of the 400ft length of pipe is 5/8" you`ll have 65 sqft of surface area. Assuming the pipe has zero insulation value and the water/soil temperature differential is 20F, the conductive transfer will be around 21.6 btu/minute.
If you leave the 6.25gal of water in the tube for a full minute the water temperature will fall by 0.4F, subsequent passes will be progressively lower as the water gets cooler and the soil gets warmer. 20F isn`t much of a differential to begin with.
The earths core is alledgedly molten iron but who knows for sure, it seems reasonable based on the assumption its responsible for the earths magnetic field.

Nice tank Jean-Luc,
I don`t envy the poor soul that had to dig the hole for it :) Here`s a pic of my tubing before i buried it 4.5ft beneath the greenhouse floor using nothing but a spade, its not something i`d want to do twice in a lifetime.

Back to rectify a few points, - I like to give things a second, third and perhaps even a fourth thought. I guess I gave up a little too early on this-one...

1. Look at the tank I have in use, isn't that a huge cylindrical tube of around 5 feet diameter and 6 high? Is it cooling the nutrients efficiently? You bet it is....

I would bet all my money on contact surface and buffer (instead of smaller diameter and flow rate) AGAIN and still go for 1.5 or even 2 inch tubes in the future. Sure thing.
Oh ya, I know how air condenser or water radiators work, they have fine rips and small channels for a purpose. The pumps that are used aren't exactly week either, but have quite a flow rate for a purpose as well. No doubt here, if using highly conducting materials (metal) and if dealing with high temperature differences plus using mechanical energy to soup up the cooling process, fans or any kind of massive kinetic energy, - the smaller the better and the more flow rate, - the more performance.

And of course, if you transpose this model and principles to a geothermal model using highly conductive materials and relatively high energy input (in fact high performance pump only), and on top of that, digging at least 60 feet or more to get close enough to "room temperature" , - not much will probably change.

But let's see it and keep it objective and thus transpose this knowledge to what we are after in our context. A. There is much less difference in temperature even if digging a few feet deep compared to an actual geothermal unit, B. The equation of rentability is different. C. The effort and the cost has to justify the difference we may gain. D. It has to be realized with different materials and means and (in most cases at least) we are after cold and not after heat.

And yet, with all those differences we (me neither) will NOT change the laws of physics and the principles that still apply and remain then. But how much will the actual difference between the same contact surface- but with different pipe diameter exactly be?! And how much difference will there be and how much more energy do we need to use with a more powerful pump and flow rate?

My main concerns and doubts turn around the low conductivity of the PVC pipes and the actual heat/cold transfer and exchange factor in relatively little depth. And I still wonder if the performance isn't in fact limited within these parameters already and that there is thus not enough to gain with smaller pipe diameter and more flow rate anyway. I even do not totally exclude that we may even deal with a reverse effect when using smaller pipe diameter here. And it certainly goes without saying that if 1.5 inch pipes are giving me the needed performance and wanted results, that I'd dig in and lay out a contact surface X with 1.5 inch and not even waste a thought about using any smaller diameter to get to a performance that I do not even need. Clearly, this is not about best performance but about sufficiency.

2. Indeed, the core temperature of the earth is undeniably energy (heat) and it sure is a unlimited source, practically seen, although most probably limited in an absolute sense. But that's third or forth grade if I remember well and not what I meant anyway. In this context and according to the topic, it's all about cold and cooling. And no, cold is not produced by the earth core and cold is no energy either, cold is simply the (relative) absence of heat. Furthermore, scientists are able to measure the amount of kinetic movement (energy) which equals temperature in materials. If there is no physical movement (standstill), we reach a condition called absolute zero. This happens @ minus 273 degree C. At that temperature there is a complete absence of heat/movement. Everything with more temperature/kinetic energy than that point, contains more or less heat energy. Yes that's a bit more advanced than 3rd grade I know ;-)

And yes, I am not lying either when pretending that I also knew that trees grow their roots in soil (orchids and a few other plants have them exposed to the atmosphere btw.) And yet soil is not an insulation (has never had such purpose, although it has insulating properties among others) - but on the contrary, a matter that actually absorbs moisture and cools down through evaporation of moisture. Soil is by no way an "insulation" as we understand it in this or a similar context.

Are most plants "insulated" against heat, or do they evapo-transpirate instead? The most successful, most evolved and wide spread mammals (as homo sapiens for instance) are incontestably those who are able to transpire, because they can adapt best to almost any climate. The most evolved and advanced are by no means those with the thickest skin or "insulation", or are they? Or are the fattest for instance (fat is said to be an insulation against heat loss) the fittest? Yes there is insulation in Nature, but it seems that it is certainly not the answer to everything... and thus not exactly the best argument I can think of ;-)

That's the most important points I wanted to get back at - I guess...

PS: Anyone wanting to get the volume of a cylinder (PVC tube or cylindrical tank)?
No need to cut it in pieces nor fill it with liquid!
Simply use this formula: V =(Pi)(h)(r)(r)

1. Multiply the height (length) with Pi. 2. Multiply the radius by itself
3. Multiply result of operation 1. by the result of operation 2.

Or simply use this online calculator: http://www.calculatorfreeonline.com/calculators/geometry-solids/cylinder.php

Back to fifth grade again for the occasion, or was that a bit later as well? ;-)

Here is a link that might be useful: Cylinder calculator online

"1. Look at the tank I have in use, isn't that a huge cylindrical tube of around 5 feet diameter and 6 high? Is it cooling the nutrients efficiently? You bet it is...."

Well No DAAAAAAAAAAAA. Did you just figure that out?
It's housing the entire contents of the reservoir 5-6 feet underground. If I used enough tubing to hold the entire contents of the reservoir within the tubing 5-6 feet underground, it wouldn't matter what diameter the tubing was, it would all be underground. You also have about 200 gallons of water the 300 gallons happyhydro is planning. That's almost twice the volume, and 500 gallons takes a lot longer to to heat up than 300 gallons.

Is all the water above ground when you run it through the system/s, or just a small part of it? The water that's not running through the system is at the deepest part of the IN-GROUND RESERVOIR AND REMAINING A CONSTANT COOL TEMPERATURE. Unless you have about 75% of the water above ground (With a 6 foot deep in-ground reservoir) when your running it through the system/s, it never has a chance to change temperatures much. Again go back and rethink the concept, there is nothing special about what your doing.

When the reservoir is underground, it doesn't matter what the size tubing is that your using to run it to the plants. Nor does it matter that it's only a foot or so underground. The cooling effects aren't coming from the tubing, it's because the reservoir is in the ground. If you really think your cooling is coming from your 2 inch tubing a foot or so underground, then use a reservoir that's above ground instead and just see what happens. Can you really be that stupid as to not see that.

Fact is, if the reservoir is 6 feet deep, there is no need for any trench geothermal cooling system. It would be completely redundant. We aren't talking about a system where 75% of the water is 6 feet in the ground all the times. We are talking about a system where a majority of the water is above ground most of the time. What part of that is so difficult to understand? Because you obviously have no clue what the difference is.

"Oh ya, I know how air condenser or water radiators work, they have fine rips and small channels for a purpose."

Of coarse they do, smaller transfers the energy faster. Great brain storming.

"No doubt here, if using highly conducting materials (metal) and if dealing with high temperature differences plus using mechanical energy to soup up the cooling process, fans or any kind of massive kinetic energy, - the smaller the better and the more flow rate, - the more performance. "

Well your SLOWLY getting up to speed. Metal is very efficient in heat transfer, although much more expensive, and not what most geothermal installations use. Most professional geothermal installations use the same type of poly-tubing in drip irrigation systems. And the only kinetic energy needed to cool water, is used by the water pump that pushes the water through the tube.

If you ever get it through your head that the reservoir were talking about is not 6 feet deep like yours, nor is it 500 gallons like yours, you might someday figure out what we are talking about. With the reservoir being 6 feet deep, there's not going to be much of a temperature difference at all, therefor a geothermal trench system would be completely redundant (did the light bulb go on yet). In fact any temperature difference would be negative, because the water in the reservoir would be cooler than the location of a 2 foot deep tube. Remember how that works? If the water in the tube is cooler than the sounding soil it will suck in heat. The only benefit to your tubing being in the ground is so it isn't above ground where it would be subject to more heat. You are simply insulating it from above ground temperatures, not cooling anything with it.

Because we are talking about a significant temperature difference here (unlike your with your geothermal reservoir), as you said "the smaller the better and the more flow rate, - the more performance" Daaaaaaaaaaaaaaaaa. Did the hamster finally wake up. Then once the system has reached it's maximum cooling (doesn't happen in 20 minuets), the water temperature will be basically the same temp as the temperature underground (approx 65-70 degrees) where the tubing coils are. Depending on how the above ground portions of the system are constructed/insulated etc., and with the water pump continually running, the water temp will remain that temperature consistently, even during the hot parts of the day.

"And of course, if you transpose this model and principles to a geothermal model using highly conductive materials and relatively high energy input (in fact high performance pump only), and on top of that, digging at least 60 feet or more to get close enough to "room temperature" , - not much will probably change."

Of coarse not with a reservoir that's 6 feet in the ground like yours, because there wouldn't be any temperature differential. No mater how long your trench was or, how many feet of tubing you use. Your just so self centered that you just simply cant see beyond anything other than what you think revolves around you.

"But let's see it and keep it objective and thus transpose this knowledge to what we are after in our context"

That would be great if you ever figure out what the actually context is (hint: it doesn't revolve around you).

"A. There is much less difference in temperature even if digging a few feet deep compared to an actual geothermal unit"

Perhaps on your continent, but were normal in the North America. If there was no difference, company's wouldn't spend the time and money to go deeper. The fact, is there is much more water content the farther down you go. As hex mentioned water content is extremely important in the efficiency of geothermal energy, because that's what wicks away the heat from the tube into the earths mass, and caries it away. That's why it's cooler farther down. Without the water content you just have a bunch of dirt that acts as an insulator, not doing anything and keeping the heat in the tube.

"D. It has to be realized with different materials and means and (in most cases at least) we are after cold and not after heat."

I'm glad you finally got up to speed on that issue. That using different materials will have diffident effects, and heat exchange rates? Was there any doubt about that for you. Or just pretending that everyone else is stupid again? Also I wasn't suggesting to dig all the way down to the earths core and hot lava it consists of for cooling.

"But how much will the actual difference between the same contact surface- but with different pipe diameter exactly be?"

It comes down to money. Most of us don't have all the money we want to spend, so therefore it needs to be cost effective. Smaller tubing is much cheaper, and doesn't require an expensive pump to do the same job. How much 2 inch tubing can you get for $90? Where I live I would be very lucky to get 180 feet worth ($5 for 10 feet), and if using PVC that would require connectors and gluing one in every 10 feet. $90 will get me 1400 feet of 1/2 inch poly tubing (the same type in professional geothermal installations). And with the 1/2 inch tubing I don't need a much more expensive pump either. That's what you call cost effective.

"2. Indeed, the core temperature of the earth is undeniably energy (heat) and it sure is a unlimited source, practically seen, although most probably limited in an absolute sense. But that's third or forth grade if I remember well and not what I meant anyway."

Just who ever said that was about you, or even remotely referring to anything you said? You think your so special that everything needs to revolve around you. Only such a pompas, egotistical, self absorbed person with a I am god complex such as yourself would even think so.

"cold is not produced by the earth core and cold is no energy either, cold is simply the (relative) absence of heat."

Can you so stupid. You said that you don't make things up, but that is a prefect example of just such a thing. Nobody ever said that cold is produced by the earths core. In fact my statement was referring to grizzs concerns about extracting so much cold from the earths crust (soil), that it winds up raising the earths temperature (ultimately changing the clement). My comment was to suggest that there was already an extreme amount of HEAT in the earth already. Get a Grip on reality already.

Again another STUPID misinterpretation. Nobody ever said that cold was a form of energy. I swear you must be drinking again. The process of transferring heat into cold "IS THE FORM OF ENERGY" (Thus the term Geothermal energy). Neither heat or cold is a form of energy in itself. It's when there is movement from one to the other that there's motion, and thus a form of energy stupid.

'And yet soil is not an insulation (has never had such purpose, although it has insulating properties among others) - but on the contrary, a matter that actually absorbs moisture and cools down through evaporation of moisture. Soil is by no way an "insulation" as we understand it in this or a similar context.

Are you pretending that your god again? Are you dictating what mother nature's purpose's are allowed to or not allowed to include are? You even say it here yourself "it has insulating properties," And who ever said that was the only property it had. Get A grip on reality already.

"Are most plants "insulated" against heat, or do they evapo-transpirate instead?"

Why does it need to be one or the other? Cant they have the benefit of both?

"The most successful, most evolved and wide spread mammals (as homo sapiens for instance) are incontestably those who are able to transpire, because they can adapt best to almost any climate"

Does that mean there is no possible way for a human to die or suffer stress under any type of heat circumstance. That's a very stupid analogy. People suffer all over the world due to heat related stress (even in environments there used to). And that is under natural circumstances. not when taken out of his or her natural environment, and subjected to abnormal circumstances. As in the case of taking plants out of the ground (where it's natural) and placing them in buckets above ground, where the roots are subjected to higher temperatures (especially during hot summer months). And/or watering them with water that's well above what would be in nature. Talk about a stupid argument.

"Yes there is insulation in Nature, but it seems that it is certainly not the answer to everything... and thus not exactly the best argument I can think of ;-)"

Again your the only one thinking any such stupid things. There can definitely more than one way to achieve a result. But ignoring a issue, doesn't qualify as achieving the desired result. For most of us here on planet earth, it is about the easiest, most cost effect solution to achieve that result. Where I live, insulation is an easy, very cost effective way to keep heat from radiating into areas of my system/s that I don't want it to. That results in less money and energy waists trying to compensate. And sorry I don't just pretend that heat is not a problem.

P.S. Cry me a river luches. I have known you and the way you treat people scene October of 2009. In fact that was my first interaction with you and you treated me like dirt. I I have seen you do that not only to me, but to many people time and time again, and with no regard for other peoples feelings. And your just to stupid to understand that your not what the world revolves around. You dish it out to everyone, so grow a pair already and take it like a man. Quit whimpering and crying like a little girl. A real man wouldn't be crying oh woo is me, and quit picking on me. If you don't like it you should have thought about that before becoming such a pompas, egotistical, self absorbed p***k, doing it to everyone else. Crying about it when you get treated the same way doesn't show any maturity, that's just acting like a little kid. Cry me a river, and I'll just pee in it.

Cool down and steady you nerves, take a deep breath, have a long walk. Maybe that helps to get in a different mood.

Honestly, homehydro I'd offer heIp but truly don't know how at this point and from here!

Take care of yerself my friend!

"my friend"

That's a big load of cow manure, you have never treated me like a friend. I wont treat you like one either.

Sounds like if I'd offer you a million Baht, Jeff - you would still disgustedly spit on it. Who ever has created all that opposition, aggression and fear ( I am not saying Paranoia) in you, it couldn't possibly be a single person. I don't know the reason why you are twisting everything to protect you from any other idea or thought than your own. It sounds like if every utterance from outside your mindset and approval is a menace to you and needs to obsessively be trampled down.

I recommend to look up Obsessive - compulsive disorder or OCD with Wikipedia. I believe you have become seriously sick and need professional help to actually manage this,

I clearly run out of options here, and after all: who wants to take all this crap? ;-)

"Sounds like if I'd offer you a million Baht, Jeff - you would still disgustedly spit on it.

By gorge, I think he's got it!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Yes, even if you offered me life itself.

Who ever has created all that
opposition.............None/nobody (different opinions make the world go around)
aggression........You, and all the disrespect that you spew out at me and others. I have no respect for people like that, and I show it.
fear...................None/nobody, not from you or anyone else anyway. The only fear in me is my lack of money. Well probably also the fact that I'm likely a high risk for diabetes, but I'll ignore that as long as I can.

"I don't know the reason why you are twisting everything to protect you from any other idea or thought than your own"

I have no doubt whatsoever you see it that way. I welcome other ideas, and again that's what makes the world go round, as well as gives me new ideas as well. But that does not mean that I will just believe everything anyone says either. I haven't twisted anything, and as you say I don't make things up, nor knowingly give wrong information. I also never assume anyone else does either (unless there posting SPAM).

"It sounds like if every utterance from outside your mindset and approval is a menace to you and needs to obsessively be trampled down."

If explaining/discussing my position on any given subject is what you call obsessively trampling you down, then so be it. That just shows that you don't know how to communicate with adults. Instead of being happy as one adult amongst adults, you want to be the only adult amongst a group of children. That way they'll have no choice but to look up to you, and not question anything you say. That boosts your ego, and is what you need to survive.

"I believe you have become seriously sick and need professional help to actually manage this"

This is exactly the way I would expect you to respond. You simply cant stand the fact that I'm not one of those children that need to look up to you. You need to be on top of a pedestal, with people looking up to you. But I'm the person that will kick that pedestal over because I refuse pray to you, or anyone else. Not even if you have a gun in my face, (as I have told you before). And the more you demand I do, the harder I'll kick that pedestal over.

"after all: who wants to take all this crap?"

You can dish it out, but just don't feel you need to receive it. I told you many times that I will never forget, you must have thought I was joking. You get back what you dish out from me, and you have dished out quite a bit in the past year and a half that I've known you. You have a lot more coming before I can call it even. So cry me a river, and I'll pee in it.

Lets try to get the thread back on topic.
Last summer i had a 30L tub outdoors with maybe 20L of nutes in it, a pond pump and a single 360 degree spinner running 24/7. The nute temp must have hit at least 90F on many occasions from sun and heat from the water pump.. i made no attempt to keep it cool :)
Identical 30L tubs filled with compost didn`t produce as many tomatoes, needed more attention and succumbed to late blight. The toms in the aero setup showed the first signs of blight a month later. I guess the compost may have been to blame even though it was new stuff.
The point i`m making is you may not need to cool the water by as much as you think :)
This season i`ll be growing toms outdoors with high pressure aero in 500L (128us gal)root chambers, it`ll be a lot more challenging in the heat.

Had no idea that cooling nutrient solution in hydro could be such a contentious subject. All of the feedback is appreciated. I am putting this system together and have a 350 gal reservoir which will be buried in the ground.I am wondering if I could cycle the pump off and on. When the pump cuts off the solution will siphon back down in to the reservoir leaving each bucket with a little bit of solution in the bottom. The roots would be coming out of the net pot and hanging in the air kind of like aeroponics during the off cycle.This will save money as the pump is 1300 watts and also give the solution a cool down period whether from the buried res or any geo thermal loops. What do you guys think, will this work and if so what is a normal cycle time for ebb and flow?Thanks,willyt

"what is a normal cycle time for ebb and flow?

Well there isn't really any "normal cycle" for ebb and flow (or any other system for that matter). It's really a trial and error process, because everyone's individual conditions are different.

"When the pump cuts off the solution will siphon back down in to the reservoir leaving each bucket with a little bit of solution in the bottom."

This little bit of solution at the bottom will heat up faster because there's less water volume.

"The roots would be coming out of the net pot and hanging in the air kind of like aeroponics during the off cycle"

Yes, where they are much more susceptible to temperatures, and lack of moisture problems (depending on your cycle times). Also every time the system drains, it will suck in warm air to replace the water that was drained. This warm air will begin warming up the roots. But more frequent cycle times will help keep the root zone temps more consent. Also insulating the above ground parts will slow down the warming up of the water, and most importantly the root zone.

Do you really want the water to siphon back down the pipe when the pump cuts out? It seems that'd just increase the odds of a jamb to the pump.
I always let the pump add water from the top of the media, then drain out the bottom/

If filling from the top how do you drain once the pump stops?

Do you really want the water to siphon back down the pipe when the pump cuts out? It seems that'd just increase the odds of a jamb to the pump.

That's how a flood and drain system works. It siphons back down through the pump when it shuts off. Depending on design and growing medium, it could potentially clog at the tube opening, but not if screened well.

I always let the pump add water from the top of the media, then drain out the bottom

That's a drip system. No matter how the water makes it back to the reservoir it needs to be screened well. Even drip systems can clog, especially from roots growing down the drain tube (that can be a problem in flood and drain as well).

These buckets feed from a 3/4 line entering the bucket about 1" from the top with a 90 degree elbow feeding straight down into the bucket. If one adds a length of hose to this barbed elbow the nutrients will drain to however far that hose goes down into the bucket, when the pump shuts off.If the feed elbows are not lengthened no nutrients siphon back.The drain is 4" below the top and is 1 1/4". Actually have not found a suitable resevoir. Like the idea of Lucas res looks like clay,wonder if one could be built with cinder blocks and cement that wouldnt leak. Wouldnt have to be so big,4x4x4=478.72 gallons @7.48 gal per cubic ft,ought to be plenty for 48 five gallon buckets. Anyway spring has sprung and happy gardening to all!willyt

These buckets feed from a 3/4 line entering the bucket about 1" from the top with a 90 degree elbow feeding straight down into the bucket. If one adds a length of hose to this barbed elbow the nutrients will drain to however far that hose goes down into the bucket, when the pump shuts off.

I had a similar setup before. Using 4 storage totes, and the feed line came in through the top using a 90 degree elbow, connected to a length of pvc tubing. I made all the lengths of pvc as close to the same length as I could. That way as long as there was water above the end of the pvc tube, it would be siphoned back to the reservoir.

However as soon as any air came into the feed lines from any of the 4 different containers, the rest would stop siphoning back. I often found some only half or partially drained, and others drained like I intended. You may wind up with a similar problem of getting them to drain evenly. I only had four containers to deal with, you will have over ten times that with 48 of them.

When i used flood and drain i just used a piece of pipe as an upstand with a hole drilled in the side near the bottom but inside the tray.
The pump would kick in and flood the tray, overflowing into the top of the upstand pipe and back to the res.
When the timer stopped the pump, the tray drained via the small hole at the bottom of the upstand pipe.
As long as the pump can outrun the smaller holes it`ll flood the trays/buckets with the bonus it will never be able to overflow.

What Hex said is how I set mine up. Water comes in the top from a 1/2" line. the I have 1.1/2" pipe with an open top to set the max fill level. near the bottom I driller a 3/16" hole to let it all drain out.
It works great with those cheap simple 15 min increment timers because no matter how long you run it, you won't overflow your system.

Grizz, Hex,
Do either of you have a picture? I don't think I'm picturing what your saying. What I picture is the water level being the same level all the time (flood cycle or not), and I don't that's what your talking about.

Its pretty simple. Its just a vertical pipe that goes through the bottom of your tray with a small hole drilled in the side of it near the bottom.
The pump fills the tray from the top with water at faster rate than than the small hole at the bottom of the upstand pipe can drain it back to the res (it drains constantly thru this hole while the tray is filling).
When the level reachs the top of the upstand pipe it flows over the top and back to the res. (tray flooded)
When the pump stops the water drains back to the res via the small hole at the bottom of the standpipe.

If it fills from the top faster than it can drain, how is it that it wont ever overflow?

So you are saying that there is a second tray that is wider than the tray the plants are in. So when the tray the plants are overflows into the second, larger tray like a catch bucket? Then back down into the reservoir.

I now think I might have an idea what you are talking about. But I cant see it being used for many buckets (trays), not with the same pump anyway, unless it was able to handle a lot of back pressure.

I can create a image of what I'm picturing, but cant post it without going through to many hoops to do so.

What an interesting thread. Not only the idle mind is the devils workshop.
As this started with cooling I would just like to say, We are very fortunate to be retired with some change to waste on this Hobby of ours. We bought a chiller to handle the Texas heat but money is not our problem or reason so what the heck.
The idea of underground cooling is very intriguing and we may try it just for the adventure. With that we could expand our outdoors garden to cover the entire 105 acres, then it could become about the money. But I'm retired, so we'll just beat down the profit urges.
We are also thinking about starting a web page on aeroponics with no commercials. Our research so far has indicated the cost would be minor.
Of course we would need people like guzz & hydro to lend creditability and knowledge to the adventure but we are learning fast and threads like this are how.
"Doing 10 with no Chance of Parole"

Here is a link that might be useful:

lets see if i can organise a diagram

The top tray can be a bucket and the res can be located some distance away as long as there is some "fall" so gravity can do its thing.

Cooling is less problematic with aero as the water requirement is much lower than other hydro methods.You can insulate a small res for little cost. Its also practical to cool down the water while its enroute to the mist heads.. cooling 50ml of water just before its used is a lot more efficient than trying to keep a 100gal res cool all day long :)

I can't see any advantages in top filling, I could see the one hole getting clogged with a bit of broken off hydroton or roots though , also you wouldn't get no where near the amount of oxygen sucked into the root zone when it drains rapidly.

The small hole in the side of the large drain pipe could get clogged, that's true. But its a lot less expensive to pop out a small plug with a pipe cleaner than replace a water pump.
Also, in regards to oxygen and drainage, it doesn't matter how quickly the medium drains, when the water is gone air will always take its place (well unless you're in a vacuum or some kind of CO2 environment, but you get the idea)
Draining faster will get the air there earlier, so to speak, but EnF is very forgiving so a two minute drain vs a 10 minute drain won't really impact the plant. Conversely, the quicker draining system will begin drying out sooner, but again 2 min vs 10 min is splitting hairs.
And please don't take this to mean I think you shouldn't go with the siphon effect. I was just saying i think not using a shared line is a better design. If I'd already set it up the other way, I probably wouldn't change it until the next grow.

HH,
you said"If it fills from the top faster than it can drain, how is it that it wont ever overflow? "
it will fill faster than the small hole in the vertical pipe, but not faster than when draining through the top of the vertical pipe. here is my sketch

of course in real life you'd just drill a smaller hole, but sketchup won't allow you to do that in a cylinder.

the large vertical pipe drains directly to the rez. the in line comes from the water pump,
The overflow control works similar to the way a toilet prevents overflows in the tank.

Thanks both grizz and hex,
I get it now, I was understanding wrong. For some reason I was picturing the water coming up from where the overflow is, rather than having a completely separate feed line. It does look like a real simple setup. My only concern would be the small drain hole clogging. But as you mentioned you could probably angle a small pipe cleaner, or piece of wire or coat hanger etc. from the bottom into the hole and unclog it. Though I can think of a few ways to make a screen around the drain tube (spaced about a 1/2 inch from it) that would be fairly simple. Even so that wouldn't stop roots from growing through it, so I'm sure I would still need to unclog it from time to time. But I like the idea that it couldn't overflow regardless.

P.S. I really like Google sketchup, it's fun and fairly easy to work with, though it can be frustrating at times I'm sure you've noticed like how you cant draw on rounded surfaced. Thus you had to create another tube, to stick through the side of the large tube to show the small hole. I know it can be done but I haven't figured out how to draw hose so it curves and bends like I want it to, and I haven't taken the time to look for the videos that show how to create that effect in (in 3D anyhow). But never the less I think it's a fun program.

I recently found another free 3D program. I've downloaded it, but haven't had time to try out yet. Its called 3DCrafter (version 8) It's supposed to be very similar to sketchup and cnet's editor ratings give it 5 stars, so I look forward to using it as well. Not saying it's better or easier to work with than sketchup, but it's free as well. It even mentions you can create animated scenes. That would be cool to show water flooding and draining in systems plants growing etc..

I used to like sketchup a lot more. In earlier editions, you could insert floor plans from cad files then build houses off that. they have since removed that, but its still okay for tinkering.
To do curvy lines like a hose, first draw the curvy line, then draw a circle at the end and use follow me command. It's not perfect but is works. .. somewhat. You can't get a loop to close that way, but its otherwise okay.
While on the subject of free software, google draftsight. It's free 2D software. Works pretty well too.

hex2006-- we keep a 25 gal. rez at 65 deg. with a 1/4 hp chiller 24-7. Without the chiller this well insulated rez will reach 90 deg. by afternoon and that is a dangerous temp. Not understanding how you chill on the way or how you spray with 50ml. Our pumps spray 1200 gph on 32 plants 1 minute at a time. At this time we are trying to get the time off worked out as ambient temps get greater.
We are also building a Water Cooler (some call them Swamp Fans)to put in the greenhouse. There will be a lot of experimenting to get pump, fan, rez, and filter size worked out. If we could have found one that would fit our greenhouse we would have just bought it.
Probably would have been cheaper.
"Doing 10 with no Chance of Parole"

Here is a link that might be useful:

Thanks Grizz,
I will try that today, I haven't tried that yet. Also thanks for the name of the free 2D program. I downloaded it, and hope to that out soon as well.

Soyousee
I may be wrong, but I think it has more to do with the way his spray system works. He uses a pressurized tank and a solenoid switch to open and close the feed line to the sprayers. If I am not mistaken he keeps it pressurized at about 90 psi, that way he gets a real fine mist coming out of the sprayers. And if I'm not mistaken that fine mist also cools the root zone by evaporation.

You probably already know, but just in case, using a swamp cooler in a confined space will create a lot of humidity. But that's probably what you mean by experimenting to get things worked out.

My outdoor aero setup uses an accumulator, the root chamber volume is ~350gal which is room for 20 plants or so. The root chamber is fed with 24 nozzles via a 12v solenoid and a homebrew 12v cycle timer.
I have about 100ft of 1/4" tube coiled and submerged in a 10gal cooler full of cold water. The nutes take upto an hour to travel through the submerged coil on the way to the solenoid which is located directly above the cooler and the end of the root chamber.
The cooler water is partially replaced when it rises above 60F using a thermostat and solenoid arrangement. The solenoid opens and runs 50F cold mains water into the cooler at the bottom and the warmer water at the top flows out via a pipe into a bucket for use elsewhere. It only runs once or twice a day for a couple of minutes so it doesnt use much but i dont let it go to waste.
I do run drain to waste nutes so i don`t have to deal with any warm water coming back.
I know there are easier ways of growing veg but its not as interesting.

I see from the res pic you are using a tubular setup, the air/water must get pretty warm inside the tubes during the day as there doesnt seem to be a lot of room for roots and airflow. You will get an idea of the space i use for roots and mist from this pic i took when i built the chambers.
They are now insulated with 2" styrofoam with a radiant barrier and clad with white pvc siding.
{{gwi:1001515}}

Happyhydro, do you have pictures of your setup?
Anybody else have pictures of their bucket setup? I would like to do an outside bucket setup for cucumbers this spring. I grew some cucumbers in the green house (10' x 20') this year, but they take up HUGH amounts of room that I don't have.
As far as cooling our solution, I too have a heat problem with the solution getting rather warm. I am going to bury my containers this year (55 gal drum, and two 35 gal drums). This will give me a cooler solution for just my labor. A side benefit is that it also gives me more height for my tomatoes. (Greenhouse is only 7' tall in the middle).