Review on 🐠 Efficient FREESEA Aquarium Heater with Submersible Thermometer - Choose from 25/50/100/200/300 Watts! by Ellie Parra

I bought this heater for a new aquarium project. The tank was an Aqueon 5 Gal Mini Bow and the concept was to feature a male rooster and a small number of compatible tank mates. The use of live plants for decoration and to improve water quality. Since the aquarium population needs to be stable after the initial introduction of fish, I wanted to avoid using medication and used a UV clarifier in case IR or other diseases caught it. Keeping the water temperature constant was an important part of the plan, so I looked at the small heaters available. I have chosen not to use a non-controllable heater or a heater pre-configured as non-controllable. I chose the FREESEA 25W immersion heater mainly for its compact size and temperature control. The included thermometer was a bonus. I was aware of numerous reviews complaining of overheating and poor regulation, but I could see that the common denominator here was that the temperature scale markings didn't match the actual temperature settings received. Many reviewers were happy with the purchase, so I moved on. I bought a heater to replace it. Looking back, I can say that it was a good decision. I set up the aquarium with the power filter switched on and used the betta and 5 small luminous tetras on the first day. After 2 days I added 3 neon tetras and that basically completed the setup. The heater was well packaged and just the right size for the aquarium. I noticed that when setting the starting temperature, there was quite a bit of play in the adjustment knob before the light on the heater turned on or off based on your input. In other words, you can turn the knob 1/8 turn in either direction before the heater turns on or off. If you were to look at the markings it would mean that you can go from 73F to 84F without any heater impact. It was confusing. I expected him to reply immediately and confirm that you made changes to the temperature settings. In the end, I settled on the middle of the free spins area and left it there. I checked over the next few days and the heater was able to maintain the advertised temperature of 29.8°C throughout the day, correctly compensating for AC cycling etc. On day 3 I noticed white spots on one of the neons and immediately applied them. my contingency plan. I removed the surge protector and replaced it with a Green Killing Machine 3W UV Sterilizer. While the plan is working, white spots initially spread to bettas and a few neon tetras, but now the Ica infection is under control and there are no longer spots on any of the fish at this time. I will wait another 2 weeks to ensure the parasite has completed its life cycle and then remove the UV light. Let's get back to the heating report. Around day 2 I noticed the formation of a film on the water surface. I quickly removed it (by placing a paper towel on the surface) and kept an eye on it. The film was not oily but looked like a thin hard surface contamination. When I picked up the paper towel, small fragments were left inside. Imagine a broken miniature ice field in the ocean. In any event, since I introduced a brand new heater and UV sterilizer, one or both of them may have released mold release agents or plasticizers from their many plastic parts. I thought it was temporary and would go away on its own. As the days went by the problem with the film on the surface got worse. Had to clean often. I was in the process of installing other digital thermometers I bought to test (more on that later) when I noticed something was growing on the top cap of the heater. Surrounding the heater's black top cover was a translucent layer about 1/4 inch thick. The substance was gel-like and slimy. He also had an unpleasant odor. I removed the heater and cleaned the lid to remove the material. I put it back in the tank and also increased the temp a bit to shorten the ick cycle. The next day the temperature rose to 84F. This is at least a 5 degree change at the minimum turn of the temperature knob. After re-reading the reviews about the heating element, I decided not to risk it anymore and pulled the heating element out of the tank. When I turned off the heater, I noticed that in just 24 hours the top end cap was already covered in a nasty slimy substance. Not good! Oh yes, the thermometer. At about the same time as I bought the heater, I bought three AQUANEAT digital thermometers. These units are essentially identical to the FREESEA unit that came with the heater. When they arrived I went ahead and mounted them on the tank to test them and they were all within 0.3 degrees of each other. The FREESEA thermometer is at least 2 degrees higher than all others. If you browse reviews on this site you will see all the complaints about how difficult it is to reliably set the temperature on this heater. Has anyone else encountered the issue of the surface film and slimy coating on the heater end cap? Posted a photo of the condition. Looks like what happened to mine. I can confirm both points. While the heater was able to maintain what I now know is about 77F, I can't imagine needing to worry about a small touch of the temperature dial raising the temperature 5 degrees or more . That's not for me. It's not worth the risk. As for the thermometer, it would be nice if it was more accurate. Can't comment on battery life and reliability as I've only had it for a few days. I only turned on the thermometers when I needed to check the temperature. Under such conditions, it may take a long time before the battery needs to be replaced. We hope these comments are helpful to you. I'm disappointed it didn't work for me.