What a 'cool' idea! hehehee...
When we first built our GH here in Arkansas, we never knew how hot it would get. In Virginia we had a big salt-water reef tank, but took it down before we moved. Anyway, to help keep the GH a little cooler in the hot summer months, we put the reef chiller on the kool-cell recycle water bin. It kept the water cool, but not really cold. We ended up adding in a huge air-conditioner to remove the humidity from the GH so that the kool-cell could actually cool the room the way it was intended. Eventually, the chiller wore out and we never replaced it (expensive & not really sure it helped all that much in the long run since the water in the kool-cell recycle bin was replaced as it evaporated throughout the day.)
I hope your expirement works. if so, package the idea and sell it! I know I want to be able to grow the cool growers. I have always wanted a Dracula. Maybe with your invention.....!