Review on 🐠 Efficient Heat Control: Hydor Submersible Glass Aquarium Heater - The Original Theo by Jordan Rini

I have had several of these heaters over the years. They worked great for my 3-6 gallon betta tanks. I like that they have controls while most heaters of this size have presets. The temp might be a few degrees higher than I set, especially on 3 gallon tanks, but that's easy to explain. They kept my aquariums at a consistent temperature, which was my number one goal as temperatures in my home fluctuate wildly, especially in the winter. All in all they were excellent heaters and I have recommended them to several people. BUT. I already have 4 of these heaters fixed. The first was not tested on a 3 gallon tank for a few days. I knew I had a problem when I literally FELT the heat coming out of the tank. The temperature of the tank exceeded 100 degrees and my rooster obviously died. I assumed this was an isolated incident, so I continued to use other heaters but kept a close eye on them. Since then I've had 3 more continue to heat the tank despite being much hotter than the set temp but luckily I caught them before disaster struck. After this last one I gave up and am looking for different heaters for these tanks. Reading the reviews it doesn't look like I'm in the minority on this question. It's a shame because when they work properly they are great heaters, but it's not worth the increased risk of overheating the tank.