AquaMiracle Adjustable 20W Small Aquarium Heater Submersible Fish Tank Heater Betta Heater Turtle Heater Super Mini Aquarium Heater with Digital Display Thermostat, for 2-4 Gallon Tanks

I needed something to keep my tropical 3-gal mini aquarium at an ideal temp, and this did the trick. it's very tiny, has a long enough cord to reach my outlets, and is easy to set and operate. I like that the heater itself is tiny enough that I can bury it in the substrate for aesthetics. Not entirely sure on the accuracy, as it always differs by 1-2 degrees compared to the thermometer I have in the aquarium, but as long as both readings are in my ideal range, I'm happy with it.

I have three of these heaters and they are perfect for my 3 gallon betta tanks. They are very steady and dependable, never had a minute of trouble out of any of the three. I set the temp and they run like clockwork. I'm very happy with them and I highly recommend these heaters.

Nice little heater for our 2.5gallon tank. Our Beta has been happily blowing bubble clouds since we got his tank at the perfect temp. I love that it has a digital read out.

I got my first of these Heaters near a month ago for my 1gal. Betta bowl. Nifty (neat and easy to use), it's been a perfect fit for the compact bowl space, with a digital control combining thermostat (to set the desired heater temp) and thermometer (to show the actual aquarium temp).Loved it so much, I then got a second one, this for my cylindrical 2gal. community tank which is home to six Guppy/Molly/Platy fishes. Yes, it is overcrowded but I closely monitor the tank's water quality and other parameters as well as the fish behavior there. And all the guys are doing well, as shown by their feeding habits, mobility, even schooling activity.Relying on these Heaters for keeping both of my minimal aquaria at an optimal 80°F I've felt confident that all is well. Until the last day or two… my apartment has cooled somewhat from its usual 75°F or so down to 68°F, nothing drastic. Yet the two heaters now seemed taxed to hold their spaces at the 80°F I've set. Each aquarium now hovers at 74°F, shown by the controls of each heater and verified by strip thermometers, one on each aquarium located up against the heater (at least for the Betta bowl). This is a mildly troubling issue on which I will update this review if warranted.

I purchased 4 of these for my 1 gallon tanks. The temperature is off by about 3 or 4 degrees. After 3 or 4 moths, ALL 4 of these devices stopped working. I even had my landlord out to check the outlet I was using. We determined that the fault in all 4 was in the USB outlet. I had to bend the usb plug inward to make a solid connection. I was able to return a few before the 1 month period on Amazon and got new ones. Those lasted about a week and they all went straight in the trash! Buy from a company you know and trust. DON'T waste your money on these.And of course, after the 1 month Amazon return period, there is no way to get a refund on the useless heaters.

Works as should, and not bulky. Nice build and price. The temp does seem to read accurately.

Ordered 3 of these for my betta tanks that I was having overheating issues in, and wanted a digital adjustable micro heater. Unfortunately one arrived not working giving a consistent E1 error no matter how submerged I tried it. Contracted the seller and they promptly responded and sent me a replacement no questions asked. The replacement arrived fairly quickly, and works just as perfectly as the others. So far so good! They keep steady temp and are able to be discreetly hidden behind the plants. Definitely would recommend if you have small tanks near a window or in a room that has frequent temperature swings. My boys’ bubble nests have tripled in size, lol. Thank you again to the seller for the excellent customer service!

I bought the 10W version for a 1.6 gal tank. I like its size. But there are a couple of issues. The temperature reading is not stable at all. The displayed temperature continually varies between 1/2 to 1 degree, switching the displayed temp by a tenth of a degree every 2 to 4 seconds. For example, over the course of 20 seconds it drops from 76.2 down to 74.5, then over the next 20 seconds climbs back up again. The actual tank temperature cannot be changing that much that fast. The heater was off for that range (I had it set for 72), but while it is on, the readings also vary about the same amount.Because of the variation, you cannot rely on a quick glance at the heater display to tell you the tank temp, o you are going to need a second tank thermometer.Since the heater turns on when the temp drops to .3 degrees below the set temp, you need to base your setting on the lowest temp, so you'll need to pay attention for a minute or two before you know what that is for a given tank temperature. With a separate tank thermometer, you can make this work by noting the difference between the heater's lowest read temp and the tank thermometer's reading and subtracting that amount from the desired tank temp for its setting.Also, the heater turns off when the sensed temp rises above .3 degrees below the set temp. For example, if the set temp is 72 deg, the heater turns on at 71.7 and off at 71.8. The instruction manual states that it is supposed to turn off when the temp rises above the set temp (which would be at 72.1 if it was set for 72.)Given the sensor variability from the actual tank temp, as the tank temp first drops below the set temp - .3 deg threshold, the heater turns on, but will then turn off right away as the sensed temp climbs above the threshold. The heater would not be turned on continuously until the tank temp actually drops 1 degree below the set temp (so that the reading variation would not be enough to turn it on again).I can't think of a reason why the temperature readings should vary this way, perhaps my unit is defective?

No duró más de dos días cuando explotó dentro del nanoacuario, al parecer el cristal no es de buena calidad o venía defectuoso

Fácil de usar

muy lindo, solo que tuve que comprar el de 30 w porque el de 10w no me iba a servir. en general es un producto lindo y práctico

Es muy limitado no llega a la temperatura que le pones ,es como para peceras pequeñas 5 o 10 lts

Si me gustó y por eso no lo devolví. Muy preciso, se puede usar para un nanoacuario. Es muy pequeño. Los que ponen mala nota es por que no saben usarlo. Lo recomiendo