Well.. if you have a fan blowing at the canopy.. it's not really blowing across the surface of the water so no, i doubt that will help. If you can't have a fan blowing directly across the surface of the water, and you have no other means of cooling the tank down even a few degrees less, than i'd say it's time to invest in a chiller. Unless you can modify the canopy to have an intake and an exhaust with fans attached to both. Intake fan to suck in cool air, and the exhaust to expel the air inside the canopy. Doing something like that would probably be cheaper then a chiller, and may drop the temperature of the tank down a few degrees.