most pumps have charts that list how much flow they'll push at various heights. just look at the charts to ensure they'll push some modicum of water at 4' (or 5 or whatever) then you can figure how long it will take to flood your system.
I have a rio and a little giant that will both push upwards of 6'+ and run in the $30 - $50 range, I think. It's been several years now. I believe they came from aquatic ecosystems.

OK, I did get a Little Giant PES-290 (290 GPH) a few minutes ago via the web. $32.77 + Free Ship. It had a max height headroom of 9', so I am sure it will do the job. Maybe you can tell me what kind of on/off cycle I would use on Lettuce, and if I could stick pepper plants in the same bed in a EnF system? I spaced my 3.75" pots 8" apart.

Thanks, Joe
PS, email feeds from these groups are very slow, or non existent. I check back often in any case.

being that lettuce is a leafy veg, they're going to like a decent amount of nitrogen. peppers, on the other hand, don't particularly like it. I probably wouldn't run them in the same reservoir. You probably can though if you set the nutrients for the peppers. the lettuce just won't be maximized.
As for cycle timings that really depends on how its set. What I'm currently growing (not a veggie(or that other cash crop either)) i run on for 30 minutes off for 3.1/2 hours during the heat of the day. I'd run it less frequently, but 30 minutes is the shortest interval on the cheapo timer I'm using.
I was growing soy with 15 on every 4 hours a few years ago without any hitches (well the deer, but that's another story)but it'll really be a function of how long it takes to flood your system and what interval your timer works at.

The timer I ordered was this > CAP ART-DNe Adjustable Recycle Timer - Product Description
The ART-DNe recycling timer controls any application requiring a device to be turned on and off at precise intervals. The ART-DNe has a user adjustable on time of 1 second to 60 minutes and an off time of 1 minute to 8 hours. A day/night/both switch allows you to select the time period that the ART-DNe will operate. The ART-DNe timers have a wide range of uses including controlling hydroponic pumps, simple CO2 controller, turning on and off ozone generators, running exhaust fans, etc. ART-DNe timers are rated for 15 amps @ 120 volts. 3 year no hassle warranty.

This will control the Little Giant PES-290-PW pump. I won't know how fast it will fill the trays until I try it, but I have one thing I can do to speed it up easily. I have my two trays in a frame I built to hold them, and give me a working surface to the front, and a bigger one to one side. I supported it with 4 cinder blocks. If the pump does not fill fast enough, I can reduce the height by the height of one cinder block. This should increase the flow by a noticeable margin.
Thanks for all your help, it is deeply appreciated.

You will have to learn how to read pump curves and answer your own questions.

Pick a volume, pick a pressure

Pressure isn't what I need, I think a volume that would take a reasonable time to fill the trays to the proper level is the focus. I will test a few pumps and stop when I get it right. Is there any web data on watering cycles? How about how high to bring the nutrient level to set my over-flow tubes?
I included pictures of what I accomplished with the help of the kind people in the Hydroponic group.

Here is a link that might be useful: Hydro Table

That's a nice clean looking setup. As for water level in a flood and drain system (ebb & flow), you generally want the water level to be about one to two inches below the top of the growing medium. The idea is to get the main root ball wet, but keep the stem dry. Otherwise too much regular moisture near the top of the growing medium can lead to stem rot. I prefer to make things like overflow settings adjustable when I can, so I can change them while the plants are growing when needed.

As for watering cycles, that's really up to the grower. There are so many variables in play, that there just isn't any specific cycle. Like watering a potted plant, there's no chart for that either (too many variables). But like watering a potted plant, the idea is to keep the root zone moist so the roots don't dry out, but not so much you suffocate them. You only really need to flood the system long enough for it to overflow, so the roots get saturated (so however long it takes to flood your system).

But there are a lot of variables like temperature, humidity, type and amount of growing medium used, size of plants etc. etc.. That there is no one best flood and drain cycle for everybody's situation. So it's best to try different flood cycles, and see how your system and plants respond. Then refine your flooding cycles based on the plants responses (and available timer settings). I generally start with a 15 or 30 minute on/off cycle (because that's my minimum timer on/off intervals). Then stretch out the off time setting (time between flooding's) and see how the plants respond. Like 30 on and 60 off (with a 30 minute minimum setting timer). If the plants begin to look weak, limp, or the growing medium feels too dry (down near the roots), I'll go back to a 30 on/off cycle. A timer with 15 minute minimum settings will give you more flexibility in your watering cycles, than a timer with 30 minute minimum settings will.

As for deciding on a pump, I always choose a pump with the highest head height as I can get first (in my budget), then GPH rating second. Because head height is the single most limiting factor (even in their GPH output). The other reason is if I ever want to expand the hydro system, or want to use it for a different system, I'm much less likely to need to buy a new pump. If the pumps output (GPH) is to high for my hydro system, it's easy to adjust it lower, but you can never get it to pump more than it was built for. Adjusting it lower can easily be done by putting in one or more "T" connectors (to split water flow in 1/2), and running a line directly back to the reservoir. Another way is using a in-line "ball cock valve," and just like a faucet, adjust the knob down to the desired water flow.

P.S.
If you keep about a 1/2 inch or so of water in the bottom of the tubs, the roots that hang down through the baskets will have access to water between flooding cycles. Otherwise they will dry out much faster than the roots in the growing...

I forgot to mention another simple solution to using a higher output GPH pump. Probably even the simplest one is to enlarge the overflow. By making the overflow side of the system at least twice as large as the flooding side, it will be able flow out faster than it can pump in.

Thanks for the great ideas. I will test the three pumps I have coming and see if any perform well right out of the box. The over-flow is the same size path as the input, but it has gravity working for it, and working against the pump. So only a good test will tell. I could put two over flow pipes and dump it into a 1" conduit to the tank. I would use rigid PVC for that.
Today I put my hand on the working surface of my hydro table and cooked it. I bought white paint to paint it white in the morning.
Thanks for all the tips on watering. The time I bought is a favorite for Hydroponics use. If you look back a couple of messages in this thread, I mention the Little Giant pump I bought, and the timer. I have one more much bigger pump, and a smaller fountain pump that still did not get here. I have 20 liters of clay balls, a giant brick of Coco Coir, and 16 various types of salad greens just sprouting. I am eager to get it all going, and looking forward to my first dry, no, wet run to make some adjustments. Tonight I cutout a lid for a 5 gallon bucket for a 5" net pot. I thought it was going to be for a tomato plant until someone said that 5 gallons won't be enough for it. It could be used for some bell pepper plants I have just starting. From the feedback in this thread, I know I will need a separate nutrient source, pump and timer for the buckets.
Thanks for the education, I hope I have something to show for it in a few weeks.

you should always try to make your overflow larger than your inlet. While gravity is helping the ouverflow, many pumps move a lot more volume than gravity pulls down.

I may have to add two more overflows. It will be easier than finding 1" pipe, and water tight connectors.

I am putting a single 5 gallon pale into operation as a DWC system with a single pepper plant. I have the air stone mounted dead center of the bottom of the pale, and I have a 5" basket mounted in the center of the lid. My question is about how high the level should be to work with a very young plant that has no roots that pass through the clay balls? My thoughts from other comments posted, would be to bring the level up until is almost touches the base of the roots that exist, the lower it as the roots get longer, always keeping the tips of the roots touching the nutrient bath. Can someone who has done this before give me any better information?
How young of a seeding can I start with? I have 4 or five bell pepper seedlings that are only 5 days old. I have them outside, but not in direct sun yet.
The same type of question will go for the lettuce, and other salad type greens that will go into the EnF system?

I will double my overflow path today.

Thanks, JM

For plants that don't have roots hanging out of the baskets yet you want the water level to at least be high enough to keep the growing medium moist. I personally would submerge the baskets about 1/4 to 1/2 inch. However some people like it to be about 1/4 to 1/2 inch below the baskets. And with enough air bubbles breaking the surface, providing enough splashing effect to continually wet the growing medium. Some growing mediums wick up the moisture much faster than others. Like coco coir, and rockwool soak it up faster than grow rocks. Rockwool will even become too saturated if it's submerged.

My concern in the described setup is water volume. Using a 5 gallon bucket and lowering the water level for the basket, you'll probably wind up with a 3 1/2 to 4 gallon reservoir. Depending on the size of the plant, as well as temp and humidity, the plant can drink up to half your water volume daily. That would be a design issue I would want to solve first. As well as making nutrient changes easier without disturbing a large plant (easy maintenance).

Wow! I would have never thought that a single plant could consume so much water in one day. That would have been a sad lesson for me. I was going to fill my net pot with clay balls at the bottom, and coco coir the rest of the way up to the plant. I still want to try this single plant, so I may use two 5 gallon buckets and use the second to hold an equal amount of nutrient, and join the buckets at the base so they will feed equally. I will be able to check the level without disturbing the plant, and add whatever I need at that time. With the connection at the base, I could insert a valve that would allow me to do water changes, and flush fresh water through the plant every so often.
My buddy is installing a float switch, and a 12v water valve to top off his levels when he is on vacation, or too busy to look. he is good with programmable PIC controller chips, so it will work in anyway he wants.
I had a lot of that dense foam left from my tray tops, so I made a box with a round opening at the top. It will isolate the 5 gallon pale from direct contact with the sun. The sun is so hot here, I thought the water would reach temperatures that could cook the plant, or at least be bad for the roots. The addition of a second bucket might be OK if I can shade it as well.
This single plant is a test for me. if it is successful, I will assemble something much bigger. My goal is to get a lot of the learning out of the way without damaging too many plants along the way.
In my soil garden, I built a bamboo trellis for my melon plant. If the flowers turn into fruit, I will build hangers for nylon stockings to hold the fruit. I took the stakes out from my cucumber plants and let them lay toward the trellis that is erected behind them. My Okra plant looks like it will get flowers soon, it is another fast grower. I have many potted pepper plants, and all are candidates for conversion to Hydroponics. Only about 1/4 of my salad garden seeds sprouted in the Rockwool cubes. I didn't check the PH on the water, and it was city water, so it was high. It didn't seam to matter with many other seeds, so maybe some varieties don't germinate as fast as others. Some of it is endive, arugula, and a few other types. It all came in one seed packet. I sorted seeds by shape and color and tried to use a few of each.
I love my gardening, it sure beats the stress of the rest of the week.

a pepper plant won't often consume 1/2 gallon per day. a full grown tomato plant in bloom will, but they're much larger plants. Still you are looking at only about 3.1/2 gallons of nutrient and having to add water in less than two weeks when they're at maximum production.

I will leave it as is until I get to a point where I have to make a change. Thanks for the input..

How much water any particular plant will consume varies. Not just from plant size, but also how much they transpire. Each leaf transpires, and the more leaves the more transpiring the plant is capable of.

Transpiring is also hugely affected by temp and humidity. A plant in warm or hot conditions will consume a lot more water (transpire) than the same plant would in cool conditions. At the same time transpiration is also affected by relative humidity. During dry conditions, a plant will transpire much more than the same plant will in humid conditions. Water vapor in the air (relative humidity) creates a sort of water vapor pressure. The more water vapor in the air, the harder it is for the plants leaves to exhale their water vapor (transpire). Therefor they transpire much faster in dry conditions, where water vapor/pressure is low. That also affects nutrient uptake.

One of the first lessons I hear people say they learned in hydroponics (other than how big the plants get, or fast they grow), is when they find out just how much water the plants can consume once they start to get full size. But we all need to see it first hand, even then it still can be amazing. I know not everybody grows in warm dry climates like where I live, but I have had my share of plants that have consumed 2 gallons of water "ea" DAILY. Namely, broccoli and tomato's.

My tomato plants had the largest reservoir, a 20 gallon reservoir for 4 plant. The plants never even got full size. Yet consumed so much water, the 20 gallon reservoir would be so low the pump would begin running dry in just two days. It took a minimum of about 6 gallons of water to keep the pump from running dry. That's over 40 gallons of water I needed to add a week for 4 medium size tomato plants (over 10 gallons each). Granted I live in a dry hot climate, and your results may vary.

P.S.
If you deride to enlarge your 5 gallon bucket reservoir in the future by adding another container connected by tubing. Just make sure the water circulates between them, otherwise the nutrient concentrations and pH levels wont be equal in both containers.

I got one of my pumps back from a friend. It might be too big. It can push 1500 gph to a height of 17 feet. I might use it anyway and divert some of the nutrient into the holding take for increased aeration. It is a Tetra 1500, and I used it for a pond I use to have in my yard. I still did not get the Little Giant I ordered, so that might be a better fit for the job at hand. The lettuce seedlings are growing very slowly. The radishes grew 10 times faster.

Radishes naturally grow very fast. Going from seed to harvest in 28 days. Here is a comparison to a few to a few varieties of radish and lettuce seeds I have;

Radishes (champion)....................days to harvest 28
Radishes (french breakfast)..........days to harvest 20-25
Lettuce (grand rapids leaf)..........days to harvest 40-60
Lettuce (parris island cos)).........days to harvest 65-85
Lettuce (iceberg)......................days to harvest 65-85