Excellent product

I am running two of these 400 W hydor heaters in my 75 gallon discus community tank. Two of them only to have a back up just in case and for more even heating. I run a ink bird controller that turns them on and off automatically as a extra safety so I can’t say how accurate the built-in thermostat is on these long term. I did calibrate them both individually first though and I didn’t have any problem.They are very powerful and do not have to run very long to get the temperature up. There is no glow from them at all except for the neon light which I do like very much.The safety feature of them not overheating if the water gets too low was a selling point for me. I had a fluval 300 watt melt the hanger and explode once.These heaters are right up there in quality with Fluval products. I would purchase them again.

i got this heater in july for my 5.5 gallon betta tank, and so far i’ve only had one problem with it; the top dial isn’t very accurate.When i first got it, i read from the reviews that it can be a couple degrees off, so i set my heater at 78F in order for it to heat till 80F, which worked. but then i had to plug it off for a few days since it was summer, and therefore very hot where i live so i’d only plug it in when it was colder than usual.after plugging it in later, 78F didn’t heat till 80F anymore, it was higher. so for every time i turned it off, the dial would heat up a few degrees up from what it’s set on. i recently moved to another apartment where the temperature is more stable so i keep the heater on 24/7, but it’s set on 73F for it to heat till 80F. so i’d monitor it the first week for temperature fluctuations until it stabilizes.

costly but performance is good, used for a couple of months now

From my Aquriam this heater blasted with in one hour

*Update* I bought this heater in 2016 and now it’s a little over 4 years later and it’s still going strong. I cannot speak accurately about the long term temperature accuracy of this heater only because I paired it with an Ink Bird Digital Temperature Controller (to keep tank from overheating in the event of a heater malfunction) about a year after I first installed the Hydor heater in my tank. But I can say that this heater, paired with the Ink Bird has been excellent and I’m very satisfied with my purchase. I have a second tank with another well known brand heater that I bought maybe 2 years ago that just died today. I feel that the Hydor is a superior heater and plan on ordering one for my other tank. My only regret is that Hydor isn’t sold locally so I had to buy the same brand that just broke while I wait for my Hydor to ship out.I keep my home thermostat low so in the winter, around 57 degrees. In the past, my aquarium heater struggled to keep my tank at the correct temperature. I decided to buy this heater for my 36 bow front aquarium and I have not been disappointed. It's kept my aquarium at a steady 78 degrees without issue. When we lost power for a few hours, the tank temp plummeted down to 68 degrees and the heater didn't seem to warm the tank back up once the power came back on but I turned the dial and reset it to 78 degrees and it kicked right in. It's been fine every since.

I bought this heater and it arrived quickly and intact (unlike another heater I purchased elsewhere)!I've been using it in my small 2.5 gallon tank for over a week now and I am quite pleased. I set it up in an empty tank and adjusted the temperature until I was happy with a steady temperature that didn't fluctuate.After about 24 hours of it remaining steady I put my Betta back in to enjoy his newly, stable home. I wanted to he sure he would be safe before placing him back in. The temperature gauge is off by about 2 degrees, I have it set at 82 and it remains steadily at 80.The heater does not burn the silk plant beside and in front of it and it has not damaged the acrylic siding of my tank. It is about 7 inches long and fits perfectly in my bevelled top tank, slightly on an angle (I also have quite a bit of gravel on the bottom and I didn't want to risk burying the end of the heater in it). The temperature gauge is easily adjustable and it DOES work in Canada (I made the mistake of buying a 240v heater, which doesn't work in America, before).I have given it only 4 stars since the temperature gauge isn't 100% accurate, otherwise I'd have put 5 stars. I highly recommend this heater, especially for small tanks! It is so hard to find a small, adjustable heater, especially for a decent price. This heater is great, I highly recommend it!

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:)

I have used hydor heaters before and found that the heater was always able to maintain a constant temperature. I have two tanks side by side right now. A 6 month old 20 gallon tank with 100W hydor heater where temperature is always at around 80degrees and a newly setup 65 gallon tank with this newly bought 300W heater.I bought this 300W heater because i was so impressed by the performance of 100W heater. I set it up at night with room temp at 74. In the morning, this 300W heater had bumped the temp up to 85 degrees. This is scary. While the heater does go off from time to time, the temp remains at 85. The temp in 20 gallon tank is 80.Both the 100W in 20 Gallon tank and the 300W in 65 Gallon tank have heaters temp knob setting at 79'F.This is very unreliable. Tanks are right next to each other. This should not be happening. Good thing i checked the temp before i went out to buy fish for the new tank.With two tanks in same room temp and same temp setting on the knob, the heaters should work identically. 5 degrees up is wayyyy too high.Previously I have always appreciated hydor accessories. Maybe i have a bad unit.UPDATE: DISASTER...Never again will i buy a hydor product. The smaller heater has given up as well and ine morning when i looked inside the tank, the temp is at 92'F. EVERY LIVING THING is dead.

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.