When it comes to heating a tank the only thing I have founf that is less reliable than any brand of heater is almost any brand of thermometer. I finally reached the point where I buy the least expensive heaters and thermometers and then I spend up for digital heater controllers. These help protect against over heating and as a failsafe I set the heater temp a degree or two above the temp. I have set on the controller.
The nice thing about the controllers I use is they display the tank temp. However, the brand I chose use C not F. But that is actually an advantage for me. Fish do not requite and exact temp. they can be fine in a range. If I set a heater at 28C that targets the temp. to 82.4 F. If the unit worked on F, I would not have much leeway on the range if the heater will go on if the water temp is 1 degree warmer or cooler than the device is set. The only way to expand this is to buy a more complex to set controller. That is more work that I want.
But If I set at 28 and the heater will turn on or off at 1 Degree C above or below that means the range in F will be 80.6 to 84.2. This is the sort of range in F I actually want. My controllers are simple. Press a button and the setting goes up by 1 degree C. It cycles around 20 to 34C which is 68 to 93.3F. I do sometimes need low 90s F and 93.3 is fine for such a need.
I trust my controllers more than my heaters. But as an offshoot of wearing a belt and suspenders I have thermometers on tanks with heater controller. The biggest downside is the controller can protect against a tank getting over heated by cutting the power to the heaters, it cannot helf if a heater fails and the water temp drops.
I use this controller
https://sevenports.com/product/micro-temperature-lcd-controller-1000w-celsius/ the downside it this is the only place I can find that still sells them. My initial few cost me about $22. Then when FosterSmith was sold to LiveAquaria, this new owner put them on sale for $12 and I bought 5. A week later I realized I should have bought 10, but they were sold out and I was forced to look elsewhere. I tend to standardize equipment in my tanks as much as possible, so I have grudgingly paid up for the controllers for the last 4 I bought. I own 12 of these.
I began buying and using heater controllers after I had two catastrophic heater failures. the first took a tank to 105F and killed a wild discus pair and turned the rummynose tetras into mush balls. My Hypancistrus L450s survived and they spawned about 6 weeks later. In the second my RB line 236 breeding tank went up to 118F. The adults mostly exploded at their bellies and the 25 -30 fry were just dead. Fortunatley, I had enough offspring from them to create a new breeding group. It was also the last straw and i began getting the controllers.
One other piece of advice on thermometers. If you can, buy them at a retail store. When you look at them you will see they acan show a range of temps. I assume that the average temp for them is likely the actual temp. Otherwise i tend to assume that the temp level shown by the most of them is likely the actual temp. I have dgital thermometers on some thins but they are only as accurate as the quality of the temp. sensor allows.
does the job
