I was also wondering about oxygen/roots and how much the roots can use. Just how people add co2 to the air, wouldnt it increase yield to use bottled oxygen to supply the bubble curtains. While it might not be cost effective to do, Im only wondering about yield gains. Even if it wasnt supplied at 100% oxygen, using bottled o2 to increase the % of oxygen in the the air that the air pumps would use should increase the yield. Here is what I wanna try, There will be a mixing box, that the air pumps would sit in. The o2 will be fed into the box, while the box wont be air tight, it will allow the o2 to fill the box and surround the air pumps, which will pump that straight to my precious roots. Even a small gain in o2 percentage-wise should show huge gains in yield.......hypothetically.......whadda you guys think?

Hi darthhelmut (again),
It would appear that we dabble at opposite ends of the technological spectrum {{gwi:998412}}

From my experience with keeping tropical fish . . .
The water that is in direct contact with the airbubbles will be saturated with oxygen, and pure O2 is not going to make a difference to the level of saturation. I think you will be more succesful if you were to get more water in contact with the bubbles.
In other words: fit more bubblers.

I know more bubbles will equal more air in the water, but what I am wondering about is how much oxygen itself can the roots absorb. The proportion of oxygen by volume in the atmosphere is 21 percent, by weight in seawater 89 percent, and in the Earth's crust 46.6 percent. So only 21% of each little bubble is oxygen. I havent found any research about upping the percentage. If the equation for DWC is the more bubbles the better, a higher concentration of o2 should allow for more absorbtion. This is all still just a hypothetical, I can only dream of trying to build a system just to experiment with this, I just have never heard anything about it. If plants react so strongly to co2 at 3-4 times the natural ppm, then the same can be said about the roots and oxygen. Thats why aeroponics is the fastest way to grow a plant, the increased oxygen to the rootmass. I 'm sure nasa has research on this for growing plants in space, I just cant seem to find any on the web.

Why do the roots need oxygen?
As far as I know, oxygen is not required for the assimilation process. Besides, plants PRODUCE oxygen.
So how come this emphasis on oxygen near the roots?

greystroke,roots need oxygen, i think you might need to read more.

if you pump in o2 it will just bubble out of the resevoir into the atmosphere, thus hindering photosynthesis. but yes more oxygen to roots=better plants. when you pump in air you are helping "gas off" carbon dioxide

kinggraham69 wrote:
greystroke,roots need oxygen, i think you might need to read more.

Oh, I believe you kinggraham69! Not to believe this would almost amount to heresy.

I have read a few articles on aerobic and anaerobic respiration of the root system, and I have found that some plants can survive without oxygen, in which case it is assumed that the oxygen is supplied by the leaves of the plant and transported to the roots.
What I know is that the root cells expend energy to transport nutrients, and for that they (probably) need oxygen. But I wouldn't mind learning how exactly that oxygen is being used. Something must be oxidised to release the energy. Probably sugar.
Not so?
The expending of energy in human muscle produces lactic acid as a byproduct. Anything similar in roots?

The other strong benefit of bubbling the nutrient solution with air is that it controls pathogens and Ph.

Im thinking you would need some sort of sealed unit so the o2 wouldnt interfere with the co2 absorbtion by the leaves, plus it would be cost effective to re-trap the o2 and pump through the nutes over and over until it is used up. Were gettin way too technical for me to build it, but I know you would need o2 sensors and other cool contraptions. From everything I read on roots and oxygen, it should work extremly well. Although plants do take in atmospheric nitrogen and convert it to use to grow, so I dont think 100% o2 would be that benificial, just as supplementing co2 at 100% would be bad for the plants. Greystroke, we may be at differnet ends of the technical spectrum, but Im no expert either. I have built different hydro set-ups, and they all worked( to some degree, Im not perfect!) But I am driven by the need to get the most outta what Im doing. I dont know why, but if there is a better way to get more outta something, Im willin to give it a shot. Im more focused on my dirt garden now that its the season, but come winter, when I move indoors, I'll get the pics( I may know how to build a cool hydro system, but computers are foriegn to me, I still type with my index fingers and dont own a digital camera just yet) of my table.
P.s. I just thought, the o2 wouldnt interfere with the co2, since co2 is heavier, the o2 would just go up and out, and the co2 would fall down cause its heavier.

Greystroke, here ya go, this should help clear things up.
http://www.betterthannature.com/catalog/article_info.php/articles_id/6

Here is a link that might be useful: better than nature

why not just make a huge DWC system? simply adding a water pump and seperate resivior does not make it an Ebb&flow system. by definition, the system must ebb (water level rise) and flow (water level drop) to be considered an ebb&flow system. I could also argue the finer points of DWC being the "fastest way to grow" but we'll save that for a different thread.

What you are making is a big, overly complicated, DWC system, not a 'hybrid'. I do not see what purpose is served by adding a water pump and seperate resivior?

Example- take a 30G rubbermaid tub and add an air pump and bubble wand. now plant 11 plants in net cups in the top of it. this is how most of us do it. building the same system but only adding 2 plants so they have more nutrient solution per plant would acomplish the same thing you are trying to achieve but without all the extra cost and added failure points. in engineering- usually the simplest solution is the best.

Also...

Bartender, I'd like to have one of whatever greystoke is drinking.

I have found that some plants can survive without oxygen

no you haven't

some plants may obtain oxygen differently than others but ALL terrestrial plants require oxygen for the chemical equasion they use to make energy we lovingly refer to as photosynthesis.

sdrawkcab wrote:
Bartender, I'd like to have one of whatever greystoke is drinking.

Sorry bru. Private bottle.{{gwi:998412}}

You were quoting me out of context. I meant " . . .without oxygen around the roots". This refers to an article I read about young plants placed in agar with all oxygen removed. The plant then transports oxygen from the leaves to the roots.
And . .
Photosynthesis is the process whereby carbon dioxide is converted into sugars under the influence of sunlight while producing oxygen as a by-product.

Photosynthesis is the process whereby carbon dioxide is converted into sugars under the influence of sunlight while producing oxygen as a by-product.

you win on a technicality. :)

I stand by my stating that terrestrial plant roots need oxygen though. the equation i was thinking of was cellular respiration, not photosynthesis. In cellular respiration, which occurs in plant roots, six molecules of glucose (C6H12O6) react with six molecules of oxygen to form six molecules of carbon dioxide, six molecules of water, and 36 molecules of ATP. This can be represented by the following chemical equation: 6C6H12O6 + 6 O2 â 6 CO2 + 6 H2O + 36 ATP

back to the original topic of making a more efficient DWC system.

Look into float valves as they might help you out when tanks start to get low. I only mention this since you say that you find maintinance a pain with the DWC. Other things I found to help include rigging yourself a way to access the tank for measurments and topping up without having to lift plants up. The main trouble I see with really large DWC systems is that it is difficult to find appropriate containers for such things so most people wind up with multiple bins that become a pain to deal with.

I still have lettuce indoors in DWC but for outdoors I've switched to media filled troughs that get a continous drip or flow. So far this has been the simplest as I can hook everything up to one big resivuar and water top up happens with a float valve so I just need to check nutrient strength and pH regularly. I do have one pump for getting the nutrient up to the troughs and one air bubbler to help with airation for that system.

sdrawkcab wrote:
you win on a technicality. :)

That's big of you. {{gwi:1002854}}

Your equation gave me the idea to google for: "roots + ATP", and bingo I got the articles I've been looking for.
One is particular pertinent to the subject: The Impact of Flooding Stress on Plants and Crops It confirms your equation.
It also confirms that there IS an anaerobic respiration, but that it will eventually lead to death by "self poisoning". Interesting!

Thanks for the exchange!

IGNORE THE ABOVE LINK! (finger trouble)
Try this:
The Impact of Flooding Stress on Plants and Crops

tclynx-
Look into float valves as they might help you out when tanks start to get low.

I'm working on a simple design for building an automated float valve system to replenish hydro-nutrient tanks. I'm still in the design/build/test phase, but if/when it works, I'll post details like a parts list and instructions. I know you can buy commercial units, but i think many home hydro growers enjoy designing and building stuff as much as they enjoy the growing its self.

greystoke

lol. I think sarcasm is often lost in text based communications. I knew what you were talking about, i was just messing with you. If there is a local college near you, and you can access their library, you can learn more than you ever wanted to know about how and why roots work. I think we spent 4-5 weeks on nothing but roots when i was working on my horticulture degree. I would not recomend these college level reference books to the casual gardener becasue they are very dry, scientific data that has not been dumbed-down for the masses the way the books @ the book store have. you seem like you have a deeper interest in really understanding things so you might enjoy scientific type books though.

darthhelmut
I realized my previous post sounds really mean. i did not intend to make fun of your design, i just don't understand the function of the seperate resivior if the regular resivoir never drains? If/when you get it built we want pictures!

sdrawkcab wrote:
. . . i was just messing with you.

You reckon I hadn't noticed? {{gwi:996599}}

A float valve should be pretty easy to design and probably even build but I found some pretty inexpensive ones and decided they were worth it.

I have built some solar powered bubblers though.