question for the electrically-minded

I have been having issues with temperature swings in my tank - at night with the lights off, it sits around 79 F. But during the day with the lights on, it would get up to about 83 - so I set a fan on the timer with the lights. The fan decreases the temperature to around 76 and change. So basically my tank is swinging between 76-80 degrees each day. Not terrible, but not ideal.

Now my question - is there a way to make a DIY temperature-controlled switch to control when the fan goes on? So that, for example, the fan turns on at 80 degrees and turns off at 79, so that the temperature will be stable? Kind of like a thermostat connected to an underwater thermometer, and also to my fan? Any advice would be appreciated.

 

I don't know about DIY but there are controllers that handle that type of thing. I think there is a Ranco thermostat/controller that's relatively cheap but it might be more worth looking into a cheap controller like the Aquacontroller Jr., or the ReefKeeper Lite. Maybe you're already aware of that but just thought I'd mention it in case you weren't.

 

Thanks for your reply, Screwtape. Yeah, I know about controllers, but even the junior kind are somewhat pricey, when all I really want is a thermostat for my fan. I am looking more for something DIY.

 

not really an answer but maybe set the fan to run in 30 minute intervels while the lights are on. this would help out the swing a few degrees and should help keep a more constant temp.

 

yea scooters got an idea there! i would deff try that first

 

they make thermostatic switches to controm attic fans. you can get 'em for around $20 at Lowes or Home Depot near the attic fans. My only concern is that these are definately not made of stainless steel so corosion might take a toll after a while.

 

why cant you keep the fans on when the lights are on??? I have my fans to keep on during light period and off during night.

 

You can. His problem is that the fan is cooling it to much.

 

Theres a new reef keeper light thats only $100 that will do everything you want and more. I got a used reef keeper 2 for $25, never thought about having one before I fell into this deal, but now wont consider having another reef without one.

~Will.

 

I think you are fine. 4 degrees is about "natural". In the ocean, when I go in, in the the morning it is about 3-4 degrees cooler than late afternoon. The ocean has a temp swing. My tank (55 gal.) goes from 78-82 degrees.