I have a 29 and use 2 heaters, one on each side, Have a E200 on one side, on a slant with a long bubble wall air stone under it, then a cheaper fluval on the other side by my Fluval output. I keep my tank at 77-78 for 4 years now. Just have 6 Rasbora's, 4 Zebra Danios (who are 4 years old...