If you are a serious reefer you have serious lighting, So the heat from the lights will keep the water cool. I dont use a heater except for right now to keep my water temp right though out the night seeing how it still gets cold here. In the summer or when the temp stay's the same I will be removing mine till next winter.trreherd said::blink: Mike you dont use heaters? I would like to know y. Would you advice us(anyone on the forum setting up a reef tank) not to use heaters also? from what i hear a heater is the cheapest way to insure a stable inviornment.