I am using a 20 on my 120 gal display and I haven't had a flood yet as long as your return will break syphon when your overflow does you should be fine. _________ 120 Gal Reef Tank Born 12/06 160+ Lbs of Live Rock 80 Lbs Live Sand 25 Gal Sump with fuge 15 lbs of Live Rock and Macro (2) 250w 20K MH and (4) 65w CF Atinics (6) Moonlights Aqua C EV Skimmer (4) Hydor Korillia # 3s (1) Yellow Chromis Survived  |