I bought my tank predrilled with an internal overflow. It has 2 holes drilled in the bottom.
I had an HOB
overflow on my 29 gal
and never really liked it. I have since removed it and and just went to a HOB
filter for that tank.
*180 gal Display, 100 gal basement sump, 33 gal refugium, 3x250 MH, 2x160 VHO actinics, zoos, some softies, LPS & lots of acros and other SPS.
*100 gal prop tank plumbed into main system w/ 2x96 PC lights and 1x150 MH,