YOFOTHSAdjustable Mini Aquarium Heater 0.5/1/2/3 Gallon Submersible Small Fish Tank Heater 10W/20W/30W Digital Display Thermostat External Temperature Controller

We have a 2.5 gallon aquarium, with a Crown Tail Beta and 3 small Neon Tetras. Ideal temperature is 76F to 77F degrees. First, it’s not USB, and this operates on standard 110/120 plug. Exactly what I wanted. Installed the heater upright in one corner of the tank. I found that setting the heater to 78F keeps the water at 76.5F, measuring with a temperature probe furthest away from the heater in the opposite corner. Keep in mind that the heater is reading the water temperature at the heater, so adjust accordingly. I also use an “old school” floating glass thermometer for confirmation. It reads a constant 76+F. Setup is easy with suction cup, and adjusting the thermostat temperature is simple with pushing a button. The heater kicks on with a red light when the temperature drops 0.2F below setting, and kicks off with a green light when temperature reaches within 0.2F of set temperature. As it’s only 10w, you’ll see the temperature display drop until it heats back up. This cycle only lasts a couple of minutes. I must say, it works very well. And at only 10w, it’s not going to use much electricity. I’ll only be displeased if it doesn’t last awhile, but first impression is, it’s a winner.

I got the 30W size for my little 2.5 gal. hospital tank. It works great and doesn't take up much room inside the small tank. It holds the temperature nicely within a degree or so.

Am totally not recommend itit works only around 30 days!!!its function princible is crazy.. it will turn on/off frequently within short time

I have a 1.5 gallons and this heater is perfect in size. Water keeps at right temperature (goes up and down a little bit but not significantly) so does what is supposed to.

I spent weeks looking for the smallest heater possible for my "sea monkey" (brine shrimp) mini tank, and this is was the top pick. Delivery was fast, instructions were clear and it works great!! It was easy to set the temp (just press the button repeatedly) and quickly came to temp, especially with only having like a quart of water. I did set this for only 71 F, so be mindful when setting your temps and watch to ensure it is where you want it, but it really hasn't varied or gone more than that as the heater turns off. Overrall love it! I can't rate the suction though as I used my own.