HydorTheo Shatterproof Aquarium Heater, 400-Watt & Ideal For 80 To 105 Gallon Fish Tanks, 15.5 Inches Long

In late March 2012, I was unaware that my 2 old aquarium heaters had stopped working. I happened to notice that the water temperature was not even registering on my digital temperature strip on my aquarium front glass. This meant that the water temperature was somewhere in the 60's.Upon inspection of the 2 heaters, the glass in both of my old aquarium heaters had shattered, evidently when the water level had gotten too low causing the glass tube to break and they stopped working.I lost a few fish due to the water being too cold.I immediately searched Amazon for a brand of heaters that would be unaffected if the water level ever got too low.I found these Hydor brand heaters listed on Amazon, their advertisement stated that they would not be affected by low water levels. Unlike most other brands, they would work even if they were not fully immersed in water.On April 4, 2012, I purchased 2 of these Hydor 400 watt heaters from Amazon for my 135 gallon aquarium. For one year, they kept my tank at exactly 74 degrees year around. The tank's water temperature never varied more or less than 1 degree from the 74 degrees that I had them set for. I absolutely loved them. They were the best heaters that I have ever owned in my 40+ years of owning a large fish aquarium.Now, for the rest of the story as to why I am now unhappy with them.Our fish aquarium is located in our basement which stays at 60 degrees year around so good dependable heaters are a must. Whether it is winter or summer, our basement stays between 59 and 60 degrees constantly. 3 different furnace companies have yet been able to solve this problem but it's a great place to be when it reaches 100 degrees outside.Exactly one year and one week after installing these heaters, I decided it was time to do a total tank clean up and a 30% water change. I unplugged and removed both of the heaters and placed them on my workbench which was close by. This was the very first time that I have ever unplugged the heaters since April 2012.After I had finished with my cleanup and water change, I reinserted and replugged both heaters back in. I did not touch the settings as they were both still set at 74 degrees. The next morning I noticed that my aquarium water temperature was 82 degrees. Both heaters were running non-stop, thus overheating the water. I immediately unplugged them and let the water cool back down. After the water had cooled and reached 74 degrees once again, I plugged the heaters back in again, making double sure that they were set at 74 degrees. Both heaters came on, they were both on constantly as the water temperature rose to 78 degrees within a few hours. I adjusted the heaters to their lowest possible temperature settings and tried them once again but the heaters were still on constantly and the water temperature was once again rising.Over the next several days, I tried numerous times to manually shut them down to lowest possible temperature setting, unplugging and replugging them, moving the control knobs back and forth, but they would still heat the tank to over 80 degrees. Up and down water temperature changes are extremely hard on tropical fish.It's like the heaters were stuck wide open to the maximum temperature and the shut off sensors were not functioning. I found the only way to shut them off is to unplug them.I don't know if unplugging and removing them from the tank may have caused them to stop working correctly. Maybe I should have waited an hour or so before removing them from the tank. At any rate, I cannot use them in my aquarium any more.I have ordered two new 300 watt heaters of a different brand from Amazon. Amazon's 2 day delivery is a life saver as the heaters will be here tomorrow. I will keep the Hydors just in case of an emergency. I believe these heaters have a 2 year warranty.

This aquarium heater is good. It maintains a constant temperature. I have had no problems with it. I even left it on without water for a week by accident and it continued working just fine.

PROS: I guess the suction cups are strong.....Thanks Hydor???CONS: Not consistent temp, did not turn off when external heat rose, fluctuating temp are dangerous!MAAAAAAAAAAYBE I got a dud? But the bad reviews are plentiful.***Please note that I gave this heater a chance and tried using it for several weeks. I am returning it today.***A more detailed review of my experience below:I bout this heater to replace my preset Tetra heater. There was nothing wrong with my original Tetra; it was maintaining my tank at 77F-78F, but I just wanted to keep my Betta tank at 80F and have the ability to adjust for treatment of illnesses instead.The initial challenge I found was that the Hydor was NOT calibrated correctly. Since I had a digital thermometer (and a standard floating thermometer for a double check) I could read that although I set the heater at 80F, it was heating the tank to 83F or even 84F. This in and of itself would be fine if I could count on the Hydor to be consistent, but it wasn't...I thought could easily make up for the temp change and set it accordingly. After I played around with it a lot I finally found that setting it to 76F left my tank at 80F..... I assumed this was it's new consistent norm, but it continued to fluctuate CONSTANTLY.For reference this heater is in the back compartment of a 5 gallon Marineland Portrait tank with a baffled filter output for my Betta. I honestly assumed that I would have the opposite problem and need to heat it a few degrees higher to get the desired temp in the main tank because of it's placement.Then I got a heat wave... Mind you, I live in the Bay Area California, so if you live in a place that gets really hot this could be even more dangerous for you and your tank!!! I found that when the external temperature rose, my heater did not turn off. It would raise to 86F or even 87F when my house itself was 85F. Everything I've researched tells me that without a heater your tank with be about 2 degreesF cooler than the ambient temp in your house. This clearly tells me the heater was not turning off when the heat rose as it should.I have my fish tank upstairs so it gets warm there. I ended up unplugging my heater in the heat wave and setting my air conditioner to kick on at 78 degrees while I was at work to ensure a safe water temp for my tank.This temp fluctuation was stressing my Betta out and it definitely stressed me out for his safety!!! Not worth it!For a 5 gallon tank I suggest either the 50-watt Tetra HT Submersible Aquarium Heater With Electronic Thermostat (also purchased on Amazon for $5 less) which kept my tank at a consistent 77F-78F or doing research to find a MUCH better adjustable option than this crappy one. I purchased this off a bad recommendation... BOOOOOOOO!

Great Lil heater, keeps within 1° of set temperature.

Se puede utilizar horizontal y verticalTermostato automático muy exacto

El calentador es excelente El empaque del calentador muy fragil El empaque de DHL pésimo, la caja del calentador llego rota por fortuna no se rompió

Heating works good. Been a few months now. And it really excels in areas where normally thermostats could explode. Handled it roughy and abruptly took it out of the water more than a few times. Showed no signs of crack or any other setbacks. Recommended. Quality feels good too.

From my Aquriam this heater blasted with in one hour