I really like this little heater for my 5 gallon Betta aquarium, it has a filter but it needs a heater and I am very happy with it. You set the temperature you want and it heats up fairly quickly and stays at that temperature, fluctuating just a degree up or down and staying in the range of your setting. So easy to use, just place in the tank, plug in, set the temperature and you're done. This is a good quality heater and now my fish swim instead of just standing still.
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