Anyone Ever Found A 'temperature Switch'?

[Deus Machina]

My aquarium levels right around 81 degrees a good portion of the time. It can get plenty warmer with me, a running computer, a TV, and lights on in the room, and it was hitting 90 when it had twin incandescent bulbs in it. I, thankfully, don't have any fish in it yet.

I'd like to stick it around 78.

So, since it's going on a stand and I can hide components, I'm thinking of making a cooler. Just a pump that would suck out tank water, run it through a radiator of some sort, and then back into the tank. I obviously can't run this all day, so that comes down to attaching it to a switch that would turn on when it hit a certain temperature.

My Google-fu fails me once again, and I can't find any 'thermometer switches' for an aquarium.

Would, perhaps, one of those fan switches for high-end computers work? They tend to come with thermometer probes made to stick against solid components, so I'm not sure if they would work in the water.

On the plus side, if it would work, those fan controllers run off 3prong fan plugs and 4-prong CPU power supply plugs, and it's easy enough to find water-cooling pumps for computers now, so it would be easy to fine components.

 

[Lateral Line]

Maybe look for "thermostat" instead of "thermometer switch", I'd be really suprised if you can't find a thermostat which could be used, electronic or an old bimetallic strip model.

The switches used for computer fans may switch at too high a temperature to be of any use, and they are switching 12-Volts, not mains power which I suspect most pumps use. The switch gear would not be rated for this and burn out either instantly or at least very quickly, potentially hazardous as well.

 

[Deus Machina]

Well, I didn't expect to find a, quote, 'thermometer switch'. So I searched for 'switch +thermometer' or '+temperature', the like.

And I do have concerns about the computer fan control, too. Wasn't sure if the probes would work right, or would put a current in the water. I've seen some water cooling pumps for CPU's that run on that 12volt, but I imagine I might have a time finding one that will run enough for a full tank.

 

[Lateral Line]

But they are called "thermostat" - did you search for that? I just searched for "thermostat +aquarium" and found just what I was talking about.

 

[Deus Machina]

Alright, just spent a while searching for that. Worked well, this time around. Thanks.

Still, everything I find is preset to turn stuff off above a certain temperature. Maybe with some rewiring, I could manage to flip that, but I'm not an electrician.

Thanks, though!

 

[Lateral Line]

You could use a normally closed relay. The thermostat, when "on" would pull the relay open, switching the cooler off, when the temperature reaches the set temperature, it switches the relay coil off which closes the external circuit switching the cooler on.

 

[Tolak]

http/www.jehmco.com/html/temperature_controller.html

I'm running an ETCI on an outdoor tub for heat it will also kick on for cooling if you set it that way. It's basically a commercial HVAC controller.