pluming question for my 400Gal

[smellfishy]

I have two 2in returns that I want to run into a single pipe that will run horizontal under the tank. I have a sump, refugium, and grow out area and I want to have control over the flow ussing valves. Should I use a larger diameter pipe for the horizontal pipe?

 

[Biggie]

I got this same issue except 1.5 returns. I talked to a general plumbing contractor and he said that whenever you have 2 pipes leading into a "T" or "Y" to add the 2 dia.'s together and "T-off" to the combined total Dia. or in my case 3" pipe.

Well 3" PVC going thru my wall is a healthy hole size so Im debating just running both 1.5 pipes directly and not using a "T"

Others may chime in here and say its not necessary because you can use a ball valve to limit your flow from your returns to your sump so the total Dia. doesnt have to be your return Dia. total which I might agree also.
Keep in mind the guy I spoke with was a general residential plumber not a reefer. Hes taking into account Sewage and other codes which Im not familiar with.

My .02

 

[RocketEngineer]

Actually you need to add the AREA of the two pipes together and calculate a new pipe diameter. So to combine two 2in pipes and have the same area, you would need one 3in pipe.

A little math never hurt anyone.

 

[Biggie]

<a href=showthread.php?s=&postid=10006305#post10006305 target=_blank>Originally posted</a> by RocketEngineer
Actually you need to add the AREA of the two pipes together and calculate a new pipe diameter. So to combine two 2in pipes and have the same area, you would need one 3in pipe.

A little math never hurt anyone.

Cool thanks for this info!. Im sure many will find it helpful. I was wondering also how 90 degree elbows play into the return flow when you have this condition.

Ill have as little as possible but not sure how it will work against me for the ones I must have.