So i've got my 20 gallon tank, and a 100 watt heater (5 watts per gallon, right?). Thing is, my heater, for some reason, will never go below 78-82 degrees (not sure which bar i'm supposed to read on this adhesive thermometer). Now that I've put on my UGF and 2 power heads (which apparently create heat), my temp wont go below 80-84 degrees (again, not sure which bar to read). Is there anything bad that can happen to my fish at that temp? The temp never fluctuates, it just seems really high to me.