hygger Small Aquarium Betta Heater, Submersible Fish Tank Heater 10W/25W/50W/100W with LED Digital Display, Suitable for Marine Saltwater and Freshwater up to 5/10/16/26 Gallon

It's perfect for a twenty gallon aquarium.

Works great in 5 gallon

Good aquarium heater_ affordable, compact, and accurate.

Good affordable heater

Heat timing is terrible!I bought a 2.5 gallon tank and heater from the local aquarium with a heater that was pre-set at 78 degrees. My betta fish like the tank to be about 79-80 degrees so I bought the hygger tank heater because it allows for heat adjustments.Keep in mind, my tank was ALREADY at 78 degrees when I put the hygger heater in. How hard could it be to jack up the heat by ONE degree?? Apparently, very hard.I took out the old heater, put the new hygger heater in, and set the temperature for 79. Unfortunately, the hygger STARTS at 62 degrees and works its way up to the desired temperature. That's crazy!! Why doesn't it automatically start at 78 like every other preset heater??? 19 hours later, and my tank is still only at 78 degrees.Nowhere on the box or in the instructions does it say that the heater starts at 62 degrees or that it takes a full day (maybe more...who knows??!) to get it up to the desired temperature. I thought about leaving the other heater in the tank while I waited for the hygger to finally kick in, but I didn't want the hygger to detect warmer water and stop working (as the directions say it will do), and I didn't want to risk over heating my fish.Overall, just really poor directions and a total lack of communication on how slowly the heater would reach 79 degrees.My poor betta fish is doing fine so far but I feel bad for him having been so stressed.

After extensive research, I settled on this heater for my betta nano tank. I’ve been using it now for about a month with zero issues and the heat setting is very accurate.

Easy to use, water started getting warmer in just half an hour ! Got this for my 3 gal tank for shrimp!

This is a nice little heater. The digital readout is brigh and easy to read. It seems to be pretty accurate as it reads the same as the alcohol thermometer that I put in with it. My only complaint is that the readout & temp module is on the wrong end of the power cord. It is much closer to the plug end rather than the aquarium end so that if you want the readout near the aquarium, chances are there won’t be enough cord length to reach an outlet.