I am having serious issues maintaining a constant temp in my 20 gal and my 65 gal. I have Aqueon 200w and 300w. Here is the frustration. Ex) Temp is set at 80 degrees. Lets say the room is at 80, The heater is running bringing water temp to 84-86 degrees. There is no reason the heater should be on!!! I fooled around with the dial because I know it isn't "exact" do to the design but then I am just going in circles with it. Both tanks are acrylic with same brand of heaters. My question is what is the BEST heater out there to maintain constant temps? Please help!