Overflow Drain Pipe Sizing

[paulthomas]

My tank has four 1.5" drains, two in each external overflow. Two will be constantly running (I hope) and the other two will be back-up. I want to keep the holes in the floor to a minimum. Will two, 2" drains adequately handle all four 1.5" drains, even in the case of a partial clog?

BTW... I'll have dual float switches in the overflows to cut power to the return pump to prevent a flood.

Thanks,
Paul

 

[JayM]

depends completely on how much water you are planning to put through it......

 

[paulthomas]

depends completely on how much water you are planning to put through it......

Well, I'd like to put all of it through it.

I believe I'll be in the 750-900 gph ballpark for the return rate, which gives me ~ 3X turnover. I'd hate to do it, but to be on the safe side, should I put four 1.5" holes or two whopping 3" holes to accommodate all four drains ?

 

[Takara]

Im doing this on my new HP 50G, and Im use to my TI-83Plus, but...

4x1.5"
0.785x1.5^2 = 1.76625
1.76625x4 = 7.065 in^2


2x2":
0.785x2^2 = 3.14
314x2 = 6.28 in^2


2x3":
0.785x3^2 = 7.065
7.065x2 = 14.13 in^2


One 3" should provide the same flow as four 1.5"

 

[cujo6984]

i would go with 2x2" throught the floor what kind of drains are you gonna use in the overflow box i would combine one from each over flow to a 2" then use that as you main drain it should handle 7-800 no problem the the other 2 will be for backup

 

[paulthomas]

Thanks for the calculations Takara. I know one hole is better than two. But a 3"er looks too big.

i would go with 2x2" throught the floor what kind of drains are you gonna use in the overflow box i would combine one from each over flow to a 2" then use that as you main drain it should handle 7-800 no problem the the other 2 will be for backup

Thanks cujo. I plan on using The McReeferson Institute's Stockman Doohickey Thing Drain. I think I'll go with two 2" drains. I'll double check with Miracles on that.