Quote Originally Posted by davidstcldfl
Quote Originally Posted by bsfman
I leveled "red neck footers" yesterday, drove 24" long rebar through the centers, and cememted them in this morning.
Oh wow....you did 'fancy' red neck footers with rebar....

I built 4' x 8' x 12" grow beds....and I installed 1" drains. It actually worked pretty well. Don't remember the exact drain time, it was in the upper range, but it was acceptable.
Per Affnan...I did add a 1 1/2" X 1" reducing coupling to the top of the stand pipe. Without it and the Bernoulli effect, I wouldn't of gotten the speed of the drain time.

Bsfman.....You may be able to/should be able to, use a 3/4 inch stand pipe....like you said, your 'total volume' of the bed is approx 120 gals.
I agree, you may only be drainning, as little as 40 gallons of water.
So you think a 3/4" stand pipe with 1" reducer and 1 1/2" bell would do the trick?