Backyard Aquaponics
A place to discuss aquaponics

I'm building a specific type of shrimp farming system and incorporating a bunch of aquaponics techniques, though my main issue is height requirements. I'm putting my "tank" on a work bench which is about 2'4" off the ground. The tank I'm building is going to be very long and wide (40'x8') and about 2/3' tall. My overflow will end up being about 3' tall, giving me 3' to work with. My question is, whats the minimum height difference I can have between one end of the pipe and another to have consistent water flow. 1", 2"? I realize I'll need to do a bunch of digging, but this will highly influence how much digging I do.



Thanks!

If Stuart is around still he might be able to answer that but you haven't given enough information to figure it out. How long is the pipe, what size pipe is it and how many and what type of direction changes are you doing? You also haven't said how much water you're trying to push through the pipe and I think we're assuming this is gravity flow? Answer a few of these questions and with some luck someone may be able to help you - won't guaranty the answer will be right so cross your fingers and hope for the best.

Sorry about that!

It'l be maybe 16ish feet of length pushing 1400 GPH, gravity flow, so I assume will either use a 1.5" or 2". The direction wont be anything crazy, merely overflow out of the tank into a 55 gallon barrel.

I found an Excel spreadsheet out online that someone put together and it gives you the ability to put in different head heights and see the flow rate based on distance and pipe diameter (if you have Excel) -

http://www.koiphen.com/forums/showthread.php?141771-PVC-Pipe-Gravity-Flow-Calulator-(Hazen-Williams-Equation)

Basically the spreadsheet shows flow rate changes with the head height and diameter based on the Hazen Williams equation. Someone more knowledgeable than I am could tell you if this is the right way to figure it but it seems like they know what they are doing. You would also have to figure in any fittings like right angle fittings since these affect the flow rate too. Trapped air can also affect the flow rate so build in some leeway and try to prevent this.

In case you don't have Excel - Without any direction changes the 2" pipe can handle about 2000 gph with a 4" drop. The 1.5 inch pipe could only do about 900 gph at this drop. If you increase the drop to 6" then for a 2" pipe it becomes 2500 gph and for the 1.5 it becomes roughly 1200 gph. At around a 9" drop the 1.5" pipe becomes a viable alternative at 1460 gph while the 2" option is a bit over 3000 gph at this drop. Finally at 12" head height it's 1700 and 3600 respectively. The author says he likes to over engineer the return flow by 20 to 25% (seventh post in the link)

Hope this is what you are looking for.

This is beautiful! The post you linked is exactly what I was looking for, I'm extremely grateful!

Glad that it helped