the back of the canopy is open and the 2 fans i have are blowing in, its a 90 gallon and i'm losing about 2 gallons a day in evaperation....and i have a 6 inch clip fan in the sump if i need it to blow across the water, to cool water temp down...i guess at fist i could blow them out and if it gets to hot turn them around....since the back is open should i put them on the top or just vent the top, of the canopy, or do nothing to the top...thanks