I might just be stoned, and it could be that I'm just about to start DWC attempt 2 and lack experience, but that sounds like a pretty damn good idea. I read in Urban Garden magazine they had outfitted a old 2x2 ft freezer with a long copper pipe they spiraled nice and wide and drilled a hole in the top and bottom of the freezer and used them as an inlet and an outlet for the coil. They then filled the freezer as high as safely possible with some sort of less toxic coolant, I don't remember what, and plugged it in. Once it was cold, the freezer was placed above the reservoir. They hooked a hose to a pump from their reservoir and to the top of the freezer in the new inlet, another hose was hooked up to the outlet that was gravity feed back into the reservoir. The large spiral of narrow piping gives the water a long enough run for the water to be effectively cooled, and this chilled a 56 gallon reservoir in a greenhouse using a interesting SWC system.
The article is in Urban Garden Magazine, July/August 2010 issue. You can find a free copy in any hydro store it is sporting a orange cover. It shows fairly detailed pictures and explains it very well. If I had a working scanner I would post it up.
