i have a 40gal bow and for the past few days i have been adding about a gallon on water a day. i checked for leaks but cant find any. I have recently added a 6 inch pc fan to keep the temp at 80 degrees. does anyone know why i am adding so much water? thanks in advance.

yes, i added a fan and my evaporation has more than doubled....a top-off off is a high priority for me now

the process of displacement of heat from water is the evaporation itself.

and the evaporation is what keeps your tank cool

and the evaporation is what keeps your tank cool
well said and finish to a statement by a large mammal with short attention span.

he he he :)

My system jumps from an evap of 1/2 gallon per day in the Winter, to 1 gallon a day in the Summer.

Dave