Automatic fan control

[NanoReefer]

I want my canopy fan to come on and off with a certain range of Water temp, like 79=off and 81=on. This needs to be a budget style project I can't afford a 200$-400$ controller. Marko in my other thread mentioned this:

I use an Air Conditioner thermostat that has a metal probe. When the temp in the tank hits 80? (the temp it is currently set at), a fan kicks on above the tank. The evaporational cooling from this one 5" fan will lover the temp in my tank by 3?. But got to keep an eye on the evap. water.

I would like to know if this metal probe is in the water? (see RED text above) I am fairly sure that we can't have much metal in the tank besides titanium, right?

Anyone have any ideas? I can't run the fan all the time it actually cools my tank too much, go figure. I would really love it to be a little more automatic.

I can do the wiring myself, I have no problem splicing wires or whatever is necessary.

If you have any ideas at all please post or if you have an old temp controller or other old piece of gear that could help me out post or pm.

Thanks all
Steve

 

[Liam]

I would'nt use a metal probe.You can get a ranco controller for about $65 which will work pefectly.I use a couple and they work great.
-Liam.

 

[MarkO]

Yep, I have the metal probe right in the water. Not sure if I'm taking chances doing this, but I've never had a problem since I've installed it about 2 years ago. All I know is that the probe is neither steel nor copper. (maybe tin?).
Anyhow, I found a link on how to build on on another board:
http://reefs.org/phpBB2/viewtopic.php?t=35515&highlight=temperature

 

[agent6473]

Where do you get a Ranco controller for 65 bucks?

 

[smcnally]

One for $75 here:
http://www.automatedaquariums.com/ranco.htm
Or One for $70 in LauraD's thread here (But it may be sold already):
http://216.235.242.50/forums/showthread.php?t=12747
Not quite $65, but pretty close.