This is what I have been using. The bigger the pvc pipes the better because the water level on your main tank will not get as high and the water level on your sump filter will not be so low.
Hole Diameter = GPH
1/2" = ____
3/4" = ____
1" = 400 gph
1.25" = 600 gph
1.50" = 800 gph
Hole Diameter = GPH
1/2" = ____
3/4" = ____
1" = 400 gph
1.25" = 600 gph
1.50" = 800 gph