Substrate and under-tank heaters provide the proper temperature for the biochemical processes necessary for plant survival. While not as sensitive to drastic temperature fluctuations as fish, plants still have a temperature range of about 72 to 82 for good health. Of course, some tropical plants will need warmer temperatures, and some marine plants will need cooler temperatures. Note too that plants will not show as many warning signs of improper temperature-you will find that they quickly die. In order to decide the best way to meet your individual aquarium heating needs, you should be familiar with the equipment available for establishing and maintaining tank temperature.
Heaters do just that.
When selecting a heater, you may find a wide variety of options. There are different styles, and they are rated at different wattages. Submersible heaters have an exposed heating element, and are designed to go directly into the tank water. These are common and easy to use. In-line heaters hang on the back of the tank, and circulate the water through an exposed heating element.