JBJ Lighting JB1235 True Temp Digital Heater Controller

Don't spend very much time looking at others that can't be calibrated. It is easy to use and can be calibrated...but the same product is for sale at $20.00 cheaper and free shipping.

Easy to install. Lasted about 5 years before needed replacement.

I currently run seven of these (one shipped with out the temperature sensor, but the seller sent me one), but I'm considering taking them all out of service, because I have to keep a close watch on them after this...I have one that began to show a "HI" error reading which meant that the temperature in the aquarium exceeded 99F. Two different thermometers in the water proved that the water temperature was 78F. I unplugged the controller and plugged the heater directly into the outlet, because the controller stopped the heater from working once the "HI" error began. Then, after leaving the controller unplugged for a day, I tried hooking it back up. I noted that the temperature reading was erratic, changing up and down until it finally read "HI" again. So, I unplugged it. I emailed the company - no response. I used their online messaging page - no response. I've called several times - got voicemail.Since most good heaters include a hi temperature cut-off, this product is redundant as well as long as your heater has a high cut-off. And, if the controller stops working then the heater stops heating as well.So far the others I have are still working, but I'm going to keep a close watch on them.

Twice now (glutton for punishment) this thermostat heater controller has failed. Not immediately, but after a few years. Temp reading will read normal and aquarium water will be hotter than normal, leaving you to wonder what is happening to your fish. Checking Ph and other chemical levels. First one failed over a weekend and cooked nearly all my fish at 92 degrees F. five years ago I replaced it with the same one. This weekend it started failing. But his time water was cold. Discus fish started getting a fungus on their tails, I tried treating it. Checking water chemical balance etc... changes... Took my wifes digital cooking thermometer and checked the water temp, was about room temp. Tried to calibrate the controller. Was too far out of calibration. Got it to within 2 degrees of calibration. Compensated and set the temp to 82 which should keep it at 80. This morning the tank was at 85 degrees. Have to get rid of this controller. Try a different brand. This controller cannot be trusted. It fails slowly. I've lost too many good expensive beautiful fish because of this controller brand and model.The heater I use and plug into the controller has never failed. It's always the controller.

Very accurate. I could not find an accurate thermometer for inside my aquarium so I decided to try this. I do not use it as a heater controller but I wanted something accurate to read the temp of my tank. This was then only unit I found that was as accurate as a mercury thermometer and is consistent with the temp gauge of my my chiller. Easy to calibrate. A++ design.

Works great, instead of heater going off and on feeling it's own heat. Remote thermometer let's heater do it's job, stays on until entire tank is heated too temp. A lot of electricity is wasted during warm up of heater.

I bought this one because I wanted the magnet mount, it arrive with a suction cup mount. Do not buy this product, it is not the product advertised in the pisture.Addrd two stars. The temp readings track nicely with my much more expensive aquarium controller so thats something i guess.I gives a 2 degree swing. So if i set it to 79.1 it basically runs down to 79 and heats to 81. Not great, not terrible.

The only reason I gave it 4 stars is because it has no alarm, but the more I think about it...alarms are annoying. I bought this to replace another, more sophisticated controller whose accuracy was poor to say the least. I'd say that for the price, simplicity, and it's accuracy +/- .05 degrees this controller is great! It is easy to setup and works as advertised.