-snarf

Here are some excerpts from a Tek I'm working on putting together. I hope they help!

I use an Igloo Cool48 split top cooler, a 2 liter soda bottle, a cheap fishtank heater and a household thermometer. Get a new cooler as it will be pretty clean already and a quick spray with lysol will be all it needs. The plastic bottle should be be tall but not TOO close to the lid of the cooler, the smaller the footprint the better. I use the $6.97 fishtank heater from W-Mart. make sure you use one that can be submerged. The timer needs to be able to turn the heater on for 10 hours a day.
Now you need to place the fishtank heater UNDERWATER in the bottle. I place mine about one inch underwater. Take the cord and run it to the edge of the cooler, now mark the area where the cord passes over the cooler wall.
Using a sharp knife trim away about 2 inches of the outer insulation of the power cord, making sure it is not plugged in!. You are cutting off the outer insulation so that the cooler lid can shut tight over the wires. The two conductors are insulated and you should take care not nick this while you are cutting. If you do just wrap some electrical tape around the cut.
Now just place your jars inside the cooler, connect the heater to the timer and the timer to the wall and set it for 10 hours. I run mine from 10pm to 8am in my area. It gets down to the 58-70F range here at night in the summer and days can be from 70-100.
This method keeps my cooler between 82-87F and the water helps stabalize the temp during the day. I still check once or twice a day and on VERY hot days I put cooler water in the bottle so that the temp does not go over about 90F.

As I say, it is under construction so the wording might need some help but the method is sound.

Good Luck!
Shaker