my tank is not drilledgive me a sec.. TOXIC how big are your overflow holes? i wanted to go mag 24... but settled with the 18
I use one of these over flow boxes that has 2-1" u-tubes.... my return line is 1"pipe from the pump split into two 3/4" lines about 5'-6' long each. also my 1" ball valve is turned down about an 1/8 turn, but I could open it up all the way with no prob.

