Cistern Cooler
 

Has anyone here set up a water cooler pumping the cool water from a cistern through coils in there nutrient tank. I am just getting started with Hydroponics. I live in Mexico and on any given day my Nutrient tank is in the 90's. My Cistern in right under where I have my setup. I was thinking of pumping the cistern water through a coil in my nutrient tank if the system was closed to keep the cooling water clean I could just pump the water right back into the cistern.

It would be geothermal cooling in a sense.
What is the average temp of the cistern? I'm sure there is a scientific way of figuring out how much coil you would need to chill the nute tank x numbers of degrees.
Depending on how many gallons your nute tank you might want to test a few things out. Drop a small pump into the cistern and run the water through a coil of say 25-50' feet of pipe and see how it works out. I say small pump because there is no need to move the water that fast. It can only exchange heat at a slow rate because there most likely is not a large difference in the water/nute temperature. Your cistern is what 65-70 degrees not 40.

Last summer I used a cheap cooler and coiled tubing (with the nutes) through the ice water from my nutrient tank. It worked like a charm! I just unplugged the pump when the nutes got cool enough. It also added some air into the system as it dropped back into the nutes. I will probably start it again soon as the temp today will be above 100.

Another fairly inexpensive idea is to build a peltier cooling system. I have some parts on order to build one because I have the same water temp problem (but no cistern, LoL).

Using a couple cpu fans with heatsinks, you can build a "cold air" system, but for water cooling I am replacing the cold-side fan with a heatsink, to which I will add some copper "rods or tubing" to extend into the reservoir water and hopefully transmit enough cold via thermal conduction to keep the water temp down.

Another alternative is to use a waterblock approach, and pump water through it with another pump, or if big enough, T-off the existing main nutrient line with a recirculating line going through the waterblock on the peltier unit.

The trick is of course, to figure out how to transfer the cold temp of the cold side of the peltier into the water, and there are a lot of ways to do that. Check out youtube videos galore for peltier ideas. If you DIY, they can be very inexpensive cooling/heating setups.

Given all the variables, I just took a WAG at the size (watts) of the peltier unit. I will do some testing in various sizes of large camping coolers to see how much differential cooling I can come up with.

MJ