Most offer their tanks as reef-ready or non-drilled.
I personally don’t care for the monster commercial overflows that come with reef-ready tanks. I only purchase non-drilled tanks and drill them myself. I love Glass-Holes overflows. Small, quiet and very efficient.
I previously drilled holes in my tank a couple of times but I can't go through the agony and the stress of it might cracking. I used a diamond drill bit, the whole shubang. I'm going to call my LFS tomorrow and see if they have one and how much, at this point I really don't care about how much it will cost.
Reef ready means it’s a tank that has already been drilled with a corner of center overflow. Here’s an example of a corner overflow….two hole in the bottom of the tank….one for a “drain” to the sump, the other for return.
Yeah, but now look at the size of that behemoth corner overflow versus this Glass-Holes 1500 gph overflow…..much smaller and less intrusive. Just for perspective, this is a five foot 90 gallon tank.