HydorTheo Shatterproof Aquarium Heater, 50-Watt & Ideal For 5 To 14 Gallon Fish Tanks, 7-Inches Long

This is the best heater for small tanks, hands down. I have tried 4 different heaters for my small betta tanks, and this is the only one that works, and works great.Heaters with no temperature adjustment are worthless, I don't care what the packaging or the store clerk tells you. But finding an adjustable heater small enough for betta tanks is tricky. This one does it.I have a 5 gallon and a 2.5 gallon desktop type, and this heater works great in both of them.My last fully submersible adjustable heater (different brand) had a round knob which was slightly recessed in a plastic casing to adjust the temperature, and underwater, with wet hands, it was extremely difficult to turn. This one is designed much better, with a large plastic dial sticking up above the top of the heater which is very easy to grasp and turn. It also has a very slight click as you turn it, which is helpful for exact adjustment. It has a numbered dial, so you can choose exact temperatures.In small tanks like this, you might have to set the temperature slightly lower to get it where you want it ... for example, in my 5 gallon I have it set at 77 to get 80 degrees, and in the 2.5 gallon at 75 to get 80 degrees. But once you get it set, it stays there, consistently.It's very compact (about 7" long total) so will fit in very small tanks. It is fully submersible. It has two suction cup attachments to attach it very firmly to the tank side.Great quality, easy to use, compact, consistent. Highly recommended.

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.

I purchased this heater 2 years ago for a 2.6 gallon Fluval aquarium. It worked well and kept the water the same temperature that I set it to for a few months. I stopped looking at the thermometer in my tank as frequently because it was always the correct temperature. You absolutely must keep an eye on the thermometer multiple times a day with this heater, especially the longer you use it. Do not trust it. This heater literally melted off the fins of my betta fish while we were on vacation and didn’t leave our house’s air conditioning on. The house didn’t reach over 78 degrees, but the heater kept turning on and heating even though it wasn’t needed as the water matched the temperature of the house. I have observed the variation in temperature very often now that I work from home, and it is shocking how inaccurate and “stuck” it is. I have the heater on its absolute lowest setting and my tank still heats up to 85-90 degrees sporadically, even though we don’t let our house get over 75 degrees when we are home. I’ve gotten to where I unplug it at night because I don’t want to wake up to another stressed fish with melted fins. It’s so frustrating because our house is much cooler at night, so my fish has to be cold due to an untrustworthy heater.

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.

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

Great heater!!! Keeps the temperature I set stable even when my room temp. fluctuates, my house can be anywhere from 18C in winter (lights turn on heater to indicate its heating) to 28C in summer in which case the heater simply shuts off. Yet the water in my tank is still 26C for Lucky (my little Betta), he's quite happy with 2 heaters spaced on opposite ends which I've had there since this July. Another way I can tell it's working watching "ripples" of heat emanate from the glass part of the heater at just the right angle. Sometimes Lucky snuggles right up against it. It's important to note the "On" light is intermittent (you can see the light on the far left corner of the picture)perfectly normal. At first I thought it stopped working but that wasn't the case. So don't go by the light, check the water temp.All in all the price was good, shipping fast, good quality, functions like it's supposed to and my fish is happy and that's what counts:)