20 Watt Small Aquarium Heater Mini Betta Flat Fish Tank Heater for 2 Gallon 3 Gallon

Our 3 gallon tank stays about 82 degrees in an old drafty house where the thermostat is set somewhere between 64 and 68 all winter. Our betta is delighted!I imagine that I'll need to switch out heaters come summer/fall when we keep it warmer in the house, but I'm pleased enough with this one that I'll stick to the same brand/type.

This unit is supposed to automatically adjust to conditions and keep the tank in the happy zone for betta and other tropical fish, but it DOES NOT WORK as advertized. It works well in cold rooms to keep the temperature warm in the tank, but if your room heats up, the unit continues to provide additional heat, cooking your fish in the tank. I am so angry at myself for not noticing the signs earlier. For the record, my room never got above 75-80 degrees Fahrenheit, but looking at the temperature in the tank, it's currently 88 degrees. If you have some other low intensity heat application you need this for outside of fish care, it may suit your needs, but if you value the well-being of your bettas, keep well away from this murder device.

I got a 2.5G tank and thought I'd be fine with one of these "plug it in and forget it" heaters. Nope. I don't know why anyone would be satisfied just letting it go without any control; plus, the digital thermometer it includes? CRAP. Do NOT trust it. It sits underwater WITH A BATTERY! The screen is SUPER sensitive to touch and it's just not worth it. You're better off with one of those cheap liquid crystal stick-on jobbers. Overall there are much better small heaters out there with reliable temp control.

It works fine but I see the temperature fluctuates quite a bit between 72-85. Not sure if it’s because of the temperature of the room or what? Also, with only one suction cup at the top the heater flops around in the water

This is a great product, easily kept my fish tank at 80 degrees Fahrenheit and had no problems. The only issue is that it is missing the thermometer it promised would be included. Other than that, this product is amazing for small tanks like 1 gal and higher.

Slim design made it east to hide in the filter so it didn’t clutter up our display tank.

Nice and thin and works great on a 5 gallon tank

If it is below 67°F in my room the heater does not keep the temperature at 75°F or higher as advertised. This fish cost me $50 between him and shipping and I put the heater under the gravel for a better look and to replace it I am going to have to be really careful to not stress him out or ruin my new forming dwarf hairgrass carpet.

At first we had this little heater in a 1 gallon fish bowl. This was not the right application as the heater warmed it up too much. We have since move to a 2 gallon tank and are very happy. It’s slim design sits under the glass rocks and does not take up any space at all. Constantly holds the tank between 77 and 78 degrees. Thermometer works well and is easy to read. This little heater was a good buy.

Funciono muy bien para mi betta en su pecera de 9 litros, la temperatura que está marcando es de 77-79°F , led rojo calienta, verde que esta manteniendo la temperatura. El pero es el adaptador de corriente/eliminador, es de un plástico de baja calidad ya tiene una pequeña cuartada, pero aún funciona muy recomendado, pero hay que tener cuidado con la capacidad del agua.Actualización: El termómetro que viene incluido es una porquería llevo aproximadamente 5 meses con él y ya llevo al menos unas 6 pilas compradas ahora solo le duran unos 3 días, la medida es LR44/AG13 llevo de marcas chinas y de marcas como energizer.

The media could not be loaded. I put it in my 4 gallon tank with starting of 77°F and within just 2 hours after putting it, it almost killed my betta as the temp still rise to 83.8°F and just stop after pulling out the water.

J'ai présentement un 10L pour mon beta est malheureusement il chauffe trop pendant la nuit l'eau est monté a 32c° donc je le déconseille et surtout qu'il chauffait toujours il arrête 1 minute et recommence a chauffer

Heats to 82f best one ever had will buy one for new tank