Heating The Water in Your Turtle Habitat
Aquatic turtles need the water they live in to be of the proper temperature in order for them to live. If the water is too cold, they will get sick. But if the water is too warm, they may not come out to bask enough, which can also make them sick. Your turtle needs the water temperature to be right in order to survive and be healthy.
Like all reptiles, turtles are ectothermic (or "cold-blooded") animals. That means they can't control their body temperatures. Their body temperatures are the same as the air and water around them within a few degrees. And like all animals, they need their body temperature to be in the correct range for their biological processes like respiration, digestion, metabolism, and resistance to disease to work properly.
That's why controlling the temperature in our turtle habitats is so important: We're actually controlling our turtles' body temperatures when we control their habitat temperatures. Luckily, heating the water in our our turtles' habitats is actually pretty easy to do, once you know how.
Finding the Right Water Temperature for your Turtle Tank
The first thing you need to know is what temperature your particular turtle species needs at his or her stage of life. You can find this out by looking at the care sheet for the species of turtle that you have or that you plan to have. Austin's Turtle Page is a great resource for all kinds of information about turtle care, and they have a whole section devoted to care sheets for different kinds of turtles. So check out the care sheet for your kind of turtle to see what kind of air and water temps it likes.
Most of the more popular aquatic turtles like Painted Turtles, Red-Eared Sliders, and Musk Turtles do well with a water temperature of about 78 to 82 degrees Fahrenheit (26 to 28 degrees Celsius) when they are hatchlings. Once their carapace (upper shell) is about 1.5 inches (3.8 centimeters) in length, the temperature can be gradually reduced, a degree or so every few weeks, to about 73 to 76 degrees Fahrenheit (23 to 24 degrees Celsius).
Turtles who are sick need higher temperatures than turtles who are well. Because turtles are ectothermic animals, they can't run a fever when they're sick; so we have to raise their habitat temperatures a little to do that for them. In general, a sick turtle's air and water temperatures should be raised about four degrees Fahrenheit (about 2 degrees Celsius) from it's normal preferred temperature.
Regulating Turtle Tank Water Temperatures
The easiest way to maintain the correct water temperature in a turtle tank is by using one or more aquarium heaters. These are commonly available in pet supply stores, but you have to be careful to choose the right heater. There are two things that you have to consider.
The first thing you have to think about is that the heater you choose should have an outside covering made of metal or plastic, not glass. This is because turtles are bigger animals than fish and they have hard shells that can break the glass tube of an aquarium heater. If that happens, your turtles will probably be electrocuted and die.
The second thing is that the heater has to be powerful enough to heat the amount of water in your tank. Heater power is measured in watts. The more watts, the more heat. You need to purchase a heater of sufficient wattage to heat the amount of water that you have in the tank. Here are some general guidelines based on the amount of water:
- 20 gallons (75 liters): 75 watts
- 40 gallons (150 liters): 150 watts
- 65 gallons (250 liters): 250 watts
- 75 gallons (300 liters): 300 watts
My favorite heater right now is the Stainless Steel PTC 300Watt Digital Heater, which you can get from Amazon. It's inexpensive, but it's made of stainless steel and includes a plastic protective cage. It also has a controller that stays outside the tank so you don't have to reach into the water to adjust the temperature. It's a very good heater for the price.
If the room where your turtle tank will be is very cold, then you should use more-powerful heaters than the ones listed above. If it is very warm, you probably can use less-powerful ones.
If you use two or more aquarium heaters to heat your turtle tank, you should add up the wattages of all the heaters, and they should total at least the amounts in the chart above for the amount of water in your tank.
Because heat is so important to turtles, using more than one heater is a good idea because if one stops working, the other will prevent the tank from getting really cold. (You should still replace the broken one as soon as possible, however). Having multiple heaters also helps keep the water temperate more even throughout the tank.
Most aquarium heaters have a dial or switch on them to adjust the temperature, so it's okay to use a bigger heater than what you need. A bigger heater may also last longer because it won't be working so hard.
Water heaters made for turtle tanks usually are enclosed in a plastic housing that makes them okay safety-wise, but most of them are pre-set to a specific temperature, usually around 78 degrees Fahrenheit (about 25.5 degrees Celsius). That's fine for healthy adult turtles, but I like to be able to set the temperature myself because I also keep baby turtles (who need warmer water), and because I want to be able to raise the temperature if my adult turtles become ill.
That's why I prefer using heaters made for fish tanks, but that have tough plastic or metal tubes (or are enclosed in a plastic safety cage). As I said earlier, I especially like the Stainless Steel PTC 300Watt Digital Heater. But Aqueon Pro Heaters are also a very good choice and probably will be easier to find in local stores. Both of these heaters are well-made and durable, and they will do a good job of regulating the water temperature.
One more thing: Don't make your turtle's water temperature too warm. For most adult aquatic turtle species, 78 F. (25.5 C.) is the highest you want unless you're treating them for an illness and a veterinarian has told you to raise the temperature. Otherwise, too-warm water can encourage bacteria growth in the tank. It also discourages turtles from basking sometimes.
Regulating Air Temperature in a Turtle Habitat
This page is about maintaining the water temperature in your turtle tank. The air temperature is regulated using the lights over the basking area, and we have a whole page devoted to that. Please click here to read it.
Other Heat-Related Equipment
Thermometers are essential for all turtle habitats. We need at least two: One to measure the temperature at the basking area, and one to measure the water temperature. Most keepers use aquarium thermometers because they're easy to find and do the same thing. But as with heaters, avoid any kind of glass thermometer in a turtle tank! The turtles may break the glass and get seriously injured.
Personally, I like the stick-on LCD thermometers. They're inexpensive and easy to read. There are two different kinds, however, so make sure you use them for their correct purposes. The water temperature thermometer gets attached to the outside the tank and reads the temperature of the water behind it, and and the air temperature thermometer gets stuck to the inside of the tank (above the water line) near the basking area. The thermometers for the air temperature are usually found in the reptile departments of pet stores, and the ones for the water temperature are usually found in the fish department.
Make sure that the air temperature thermometer is a "high-range" one that can display temperatures at least as high as 95 degrees Fahrenheit (35 degrees Celsius). The water temperature thermometer should be able to display temperatures of at least 86 degrees Fahrenheit (30 degrees Celsius).
Under-Tank Heaters, Rock Heaters, etc.
Most pet supply stores sell a wide variety of heaters that fit under a tank, or which are shaped liked rocks and go inside the tank. I don't recommend any of them. They're really designed for terrestrial reptiles, not aquatic turtles. In my experience, the under-tank heaters are expensive and don't do a good job of regulating water temperatures, and the rock heaters usually can't be used underwater.