Deep is good! Thats my major complaint with my 90 with only 18" front to back, once you get your rock in there (and especially with an internal centre overflow) I dont have a lot of space. I would go with an external overflow for sure.
Maybe shallow is a bit better too for better light penetration and easier to view top down.
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- Greg
90G : Light - Tek 6xT5 | Skim - EuroReef RS135 | Flow - 2xVortech MP40W | Control - Reef Keeper 2
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