new sump help

[reefer newby]

I successfully drilled a ten gal tank. Just to see if i could. So now I am ready to start setting up another 55 gal tank. I want to drill the tank for a sump. I think I want to put the holes at the top with a skimmer box covering them. My question is , how many holes , and how large should the hole or holes be? How many gph do l want going thru the sump. The sump will be a 20 gal tank.

 

[DSP]

I would use 1 inch bulkheads,You would need a 45mm diamond holesaw.If your gunna use overflow boxes i would use 2 overflows,1 on each side of the tank so 2 holes total.Im setting up a 125 and im not gunna use any overflow boxes,Im just using strainers.Iv seen quite a few tanks that use just strainers and they work great so i decided to do it,saves more room in the tank

 

[Reefing Madness]

5-6 times your DT volume through your sump.
What physical hole size is needed for a bulkhead?