refugium and sumps

[BC_Grl]

You could probably use an external overflow instead of drilling the tank. We have an external one and I hate it!!!!! If I had any other choice, it would be -hands down- drilled. It is easier to control the return pump, and you don't have to be worried about them overflowing. And if the power goes out and comes back on, what will re-siphon it? There are just too many "ifs" if you don't.