I don't think the idea will work. Heat transfer requires optimizing several parameters, including the speed of the water or air across the surface, the temperature difference, the density of the air or water (water good, air bad), the surface area in contact with the air or water, whether the flow is turbulent or not (turbulent much better), etc. To make the air side of the heat exchanger work at all would take a good fan blowing air across/through the heat exchanger. But, just blowing that air across the water works much better because evaporating water removes lots of heat from the water compared to the heat transfer to a heat exchanger.
I suggest looking at where the heat in the water is coming from and trying to reduce that at the source. If it is from a powerhead, for example, don't use one, use an external mounted pump. If it is from the lights, move them farther from the water, so the air blocks some of the heat. And, let the water temperature drop a bit more at night, by lowering the heater setting a couple of degrees or so.