I had the same problem last weekend in my 45 gal. I used a stand fan on high with it rotating in front of tank towards the top where the lights are. I put it on a timer so it shut off at night. (I was worried it might work to well.) It worked great and didn't cost me anything as I already had the fan. (My tank runs on a power compac lighting with small fans that came with the unit. :lol: