I have a 100G holding tank bog which I am using to supply a waterfall. The inlet is a 2" PVC and two 1.5" PVC outlets to supply the waterfall. Unfortunately it's not enough to drain out the water and the water overflows. Instead of just drilling more holes. I figured to ask here instead. Should just put in a regular spillway? I didn't go that route because I couldn't figure out how to prevent leaking, so went with the PVC outlet instead. I was considering to add one 3" PVC to start, but the size is pretty tight. I'll post some pictures when I get home.