Drilling tank gph hole size

[Bouzouki]

I am building a 32 x 32 x 18 cube. I plan on drilling out the back wall to flow into sump. I will build a surface skimmer out of glass around the hole. What size hole do i need for a ehiem 900 gph pump.

http://www.reefcentral.com/calc/drain.php

I checked here and it says
Recommended minimum drain pipe diameter = 1.24 inches
Recommended minimum linear overflow size = 14 inches

What is the linear overflow spec?

so the idea is that i make a box out of glass and silicone it to the wall over the holes for surface skimer. The water will run in the box and though a hole in the side of the tank.

 

[danno14]

Linear overflow = If you make an overflow 14 inches long, with the water cascading over it. (what you are mentioning about the water running into the box. The hole in the side of the tank would then be 1.24" min (I would go with a 1.5" bulkhead). G'luck!

 

[Myteemouse]

or two 1" would work good too, but then you have to drill two holes.
I like at least two hole "JUST IN CASE"

 

[kgross]

Yes 2 inch will work. Actually they will work better. You can set one of them up as a full siphon with the second as a backup, and you can make the overflow completely silent that way.

Kim