I've also been using cold water for top off

I agree with the fan. I blow a fan across the water surface and my temp. drops 2-3 degrees, lots of evap. though.

[quote=MarkoD;729840]im running all LEDs. they dont put much, if any heat into the tank.[/QUOTE
Same here. When I had a heat problem before LEDs I would turn the ATO off and take an icecream pail of actual tank water out and freeze it. Than put the big ice cube in the sump. Rotated 2 buckets like this and it worked good for me.