Just set up a biocube 29 gallon tank. I have 20 lbs of live rock in it. Stock hood and lighting. Having a hard time keeping the temperature right. It started this morning at 78.5 and now it is at 82 degrees and stays there throughout the day. I have the heater set at 77 and its not on. Lights have been on for 8 hours. Air conditioning in our house is set at 76 degrees. Any suggestions?