I was thinking of 4 like Sam has that I seen two in each corner but maybe that is two many for a 120? one or two over flows standard in a 120? But wile I am drilling I think I would prefer to have more then needed so if I wanted to add a bigger pump later I could. Sorry I have only had nanos, so this whole sump thing is new to me? What size holes do I need to drill? Anyone got a bit laying around that they used on theres that has a couple of drills still left in it that I can use to drill mine? Did you guys buy your over Flowers or build them? Thanks Glen
Re: what size holes and how many do I need to drill for a 12 The 120 we have at the store, has four holes, two drains, and two returns. I believe the holes themselves are 1 3/4 inch, but they dont seem to flow more water, it seems to be the over flow box that matters more than the holes when it comes to that.
Re: what size holes and how many do I need to drill for a 12 We have two holes in our big tank, two in the frag tank,  and also two in our son's 29 and the holes vary from 3/4" to 1". You might come pick Blake and Mike's brain on the subject. They drill tanks fairly often and have some experience with overflows. They also have the bits.
