Recently uprgraded from a 70g corner unit ( still sitting in my garage)to a 200g system and still trying to work out the kinks. I run two 250watt metal halides and when I left the house yesterday I forgot to turn on my ceiling fan to help keep the heat down from the lights. Got home last night and found my tank to be 83 degrees it usually stays around 76 -78. All is well today fish and coral are fine Lady luck was on my side this time. :hmmmm: