Understanding the caclulators


New member
I am using the drain pipe/ over flow calc. I want to drill a hole in my tank and install two bulk heads. When I put 1100 gph in the calc it comes back with:

Using the following input parameters
Gallons per Hour = 1100

Drain and Overflow sizes are calculated as
Recommended minimum drain pipe diameter = 1.37 inches
Recommended minimum linear overflow size = 17 inches

Does this mean that if I have two one inch bulk heads and make a over flow that is at least 17 inchs long their will be enough water flow through the drain?


New member
Good luck trying to interp. what they are getting at with these recommendations.

Your going to be limited on space and each tank has its' own restrictions. If I were you I would do the (2) 1" holes and if your sump is below the display I can promise you are going to end up with atleast 17" linear drop.

It's all mostly trial and error... adjust!


New member
Liquid Hobby, that's correct.
So if you have one long over flow 17" or a box over flow like, 5" off from the back, and then 7" inches long for a total of 17"

Back of tank
5"| Overflow |5"


New member
Dang HTML won't allow me the extra spaces to show you that small diag. above..

Hope you get the idea anyways..