I was doing some maintenance in my aquarium and notice the water was extremely warm - I checked the temperature and it was almost 85F !!! Apparently the dial on my 300 watt heater was turned all the way up (it's an external round dial). My tank is usually set for around 77. I turned it down - but I'm not sure if letting the tank cool off too quick is good, but I certainly don't want it at that temperature. It had to have happened in the past 36 hours or so - but not sure exactly when. What is the best way of dealing with this? My tank is a 75 gallon. It would probably take 12 hours to cool back down to its normal temperature. Will there be any long term consequences from this?