how far down should i drill two holes in my tank? i want them on the surface but dont know how far down i should drill. i have a 30 gallon sump for a 55 gallon
overflow holes get drilled whenever you want the waterline to be unless you plan to do some plumbing inside the tank... which makes drilling the tank sorta pointless imo cuz if yer not doing it to hide plumbing then why bother risking screwing it up when you can just make an overflow with pvc for like $8
return holes can be wherever you want them to be..