Trying to add ice but I figure I need to do this slowly. I keep wondering if growing in dirt wouldn't be much easier!!!

Mike

And what I do next summer with the plants in the green house? I'm really not ready to throw in the towel - but I do need to figure out how to grow a bunch of plants in water under all kinds of conditions.

Mike

Mike

I might have to check into that swamp cooler stuff. . .

Route the air with flex duct so it leaves the space if you are worried about humidity.

You are probably right that for equivalent cooling, swamp coolers are less expensive to operate than thermoelectric devices.

However, the system that I put togather is about a 4 1/2" cube envelope and rated at about 65 watts. And as indicated in my last post, this unit has sufficient cooling capacity to maintain the nutrient solution at 12 to 15 degrees F below the high ambient air temperature. I've never seen an equivalent size swamp cooler, though it might be fun to build one.

I use a swamp cooler (1/2 hp, 4100 cfm) to cool my greenhouse (10'x12'x13'). I had considered, very briefly, running a line from swamp cooler reservoir through my nutient solution, but too much plumbing, too much heat loss and probably not enough delta T.

Yes ... allelectronics.com.

I checked on their solar panels. They have 12V-20W, 13" x 20" panels, but they are a bit pricey for just messing around--at least for me.

I am currently running my chiller day and night, but it might not be necessary to run it at night.

I know that the chiller scheme works, but THE question for me, is whether the reduced nutrient solution temperature has a significant effect on my lettuce crop yield. There are too, too many variables to run a cause and effect experiment.

I'm curious, what hydroponic system are you using for your tomatoes?

I'm using a drip system,and by the time the nutrient gets to the roots from the 15 gal reservior, via a small pressure tank, the tubing and the rockwool, I've assumed that cooling the nutrient in the reservior would have little or no effect.

I'm using the thermoelectric system to chill the nutrient solution in my lettuce raft system, which is a static system. I add 5 gal of water every week or so. When I decided that I needed a chiller, I was unaware that aquarium chillers even existed, so I built my own.

I am running an NFT system, basically 3 of the 10' 6" PVC. Each of the pipes is fed with a 1/2" nutrient line and it then returns back into the resevoir. My resevoir is way to small for my application, however, with the constant recirculation it makes the chilling easier. The nutrients aren't out of the tank for too long before they return back into the tank. I have the temp prob in the resevoir before the chiller. This way I know that the nutrient going to the plants is at least lower than 75 degrees. Lucky for me a local fish store had a huge tent sale when I was setting up my system, I knew what I was looking for and they had a chiller with no box, no warrenty, and it was also marked down numberous times. Since the refrigerent was 134A that ment even if it didn't work right I could fix it, and for 100 bucks why not ;)

Bryan

Some heat will go away with evaporation, but there are a lot of variables here, too. If your reservoir is in a heated space, it's temperature will be higher than ambient.

Most pumps used in hydroponic systems are anyway over dimensioned. Reduce the difference in hight between reservoir an outlet, replace your "domestic waterworks engine" by a tiny pump (5 watt as suggested, - as in smallest available in your local aquarium supply store) and you shouldn't even be concerned about any degree plus produced by that tiny thing.