I have a small 5 gallon tank. When I went shopping for aquarium heaters, the sales clerk recommended a compact 7.5W aquarium heater. I like the flat design because it allowed me to place the heater under the gravel. The slim and discreet design helps maintain the natural, uncluttered aesthetic I want for my aquarium.
This type of submersible aquarium heater is perfect for small tanks like mine. It can be used to keep the perfect temperature for both freshwater and saltwater fish. Aside from placing the heater under the gravel, fish owners can also opt to place it along the side of any acrylic or glass aquarium and it will still provide safe and reliable heating.