runway, unless you get a tank drilled already(reef ready) then the bottom will more then likely be tempered glass, Termpered glass can not be drilled. Getting a predrilled tank can cost more the getting one not drilled and then installing your own holes. Most glass stores drill holes..
I have them about 3" down and 4" in in both upper corners.. I'll try and post a pic later. If you don't have a RR tank IMO
this is the bast way to go..
Scho why are the tanks drilled on the back not efficient?? I belong to a club and there are a lot of members who have them set up like this with no problems. I get great flow out of 2, 1" bulk heads returns, I would say almost 1200 gph
if I have the elbows adjusted for a fater flow back.
1" hole in bottom will have the same flow as a 1" hole in the back???
Would like to know what info you have that says these are not efficient..