Hum,
I'm not quite sure how to figure pump size. I know most drip systems have a psi rating as well as GPH (gallon per hour) ratings. I have a couple pond pumps running, one feeding about 8 spray heads in a 5" pvc fence post. The other is larger and is feeding a couple 6' lengths of 1/4" soaker line as well as the top ends of a couple 6' troughs. The larger pump has a Y adapter on it that is letting about half the flow bypass and stir the resivuar to keep the airation up. You can get pressure regulators to keep the pressure from being too much for the drip lines but the bypass might be a simpler method. I think the larger of my pond pumps is about 300 GPH but the amount of rise and length of line will affect this.

What kind of plants are you planning to grow in this system? The root space could be kinda small for certain kinds of plants though it might make a great lettuce factory. Have you already purchased materials? Have you concidered open top troughs? They require more media but you can use cheaper media than the hydroton. It would save the waste of replacing the dixie cups each crop.

Thanks tclynx for your input. I will be putting beans in this system as an experament. The water line will not be rigged up with drippers it will be on a full flow system. I think maby a 300gph pump will work with 1/2 inch pipe and 1/8 or 1/4 water connections. If i need to I can put a valve and discharge some solution back to the reservoir.
Thank You
Hydro_Sam

Here are some photo's of what i did. I used perlite for the medium though (to cheap to buy hydroton). Worked really well until the tomatoes got to the fruit bearing stage, then the roots choked the system and pruning them was too hard on them and they quit producing. I used about a 200 gph pump from harbor freight that cost about $16. The overflow pipes are 3/4" pvc and they fit through grommets I got from the Ace hardware. Bevel the end of the pvc and it will slide up in there a lot easier. They allow you to adjust the depth of the nutrient solution. Deeper when plants are young, shallower as they grow longer roots. This system is called DFT, Deep flow technique. Rubbermade totes make great reservoirs.
http://zrubeks.com/hydro/100_1368.JPG
http://zrubeks.com/hydro/100_1518.jpg
http://zrubeks.com/hydro/100_1516.jpg

Sam
my little 300 gph pump needed an adaptor to be able to hook to the little y valve and then I could use a hose end adaptor to go to the 1/2" poly drip pipe. From there you just need the punch a few 1/4" coupplers and some snall sections of 1/4" tubing to put the flows where you need them.

Good luck with the beans. I got some cucs in my open top trough and salad in the pvc trough. I guess I need to take more pictures.

Flyingz,
How is your luck with keeping the nutrient cool? (by the way, what is your location) My nutrient is sunk in the ground and shaded and it still feels really warm in there when I stick my arm in to check the nutrient strength and ph. It is only April, what do I do next month? I'm in central FL.

Thank you for all this good advise. I have the system built and gave it a test run yesterday with a 218gph pump. The water pipe is 1/2" black poly pipe and the water flowed good, but to be on the safe side I will go with a 300gph pump for a bit more volume. The holes in the poly are about 1/8" diameter. (just drilled a hole at each of the 58 cup locations) To keep the solution cool you can invest in an old fridge, or the cheeper way would be to freeze water in 2 liter bottles. I am in central Texas.

Thanks
Hydro_Sam

I grow similarly with only 12 plants and use 0.3 GPM/plant site.

The primary limitation of pond pumps is that they will do only about 2 psig which will not run high pressure drop emitters.

I actually have a pond pump running about 8 sprayers. Granted that is alot of pump (300 GPH) for such a small number of sprayers but I used what I had.

so what kind of pumps should one look for if planning a large hydroponic unit?

I like the frozen bottle idea but I think the other half would strangle me if I did that with our current small freezer. I would have to let him get a chest freezer before I did it.

Hello tclynx, I wish I had more computer savy and I could put a picture of my new system on here but, well anyway this is really a big system, but I built it in a way that is not spread out all over everywhere. It is built out of three 10' sections of 4" pvc (sewer drainfield pipe that is black inside white outside)they are side by side 8" on center. It is all glued together with Ts and Ls and draining at one end back to the reservoir. The water pipe is 1/2" poly all looped together the same as the garden. The system is supplyed by a 350 GPH centrifugal pond pump and has 58 cups with a 1/8" hole drilled in the poly at each cup and in the test run it did great. I have propegated some beans and I just cannot believe that they are 4" tall and very healthy in just 3 days. I hope they do this good in the garden. Depending on how big the garden is, you may need to use a pressure pump. You can buy on demand pressure pumps but you will need to check on prices as I have not purchased that type in years. My new system is setting almost level on the saw horses I built and it drains just fine. I will transplant the beans in the garden in hydroton in about a week (when nights are at least 60 degrees) and I will let you know how it does.
Thank You
Hydro

Sounds like a nice compact little set up. Do you have support already rigged up for your beans? If not you might want to get on that pretty quickly as it gets trickier once the plants are in place and in need of the support.

I haven't yet grown any beans in such a system but I've heard of people having some major root systems on beans. The only hydro beans I grew were in a wick system and the roots pretty much filled up all the space in the 1 gallon container. Keep an eye on that since if they block up your pipes you may get some overflow issues. Good luck and keep us posted.
In cooler weather you might try something like snow peas, I've enjoyed growing them in hydro.