How to Set up a Tank for Your Red-Eared Slider Turtle

These semi-aquatic turtles need a basking area for health reasons

How to set up a red eared slider turtle tank

Illustration: © The Spruce, 2018

In their natural habitats, red-eared slider turtles are semi-aquatic, meaning they spend a good deal of their time in the water, but also spend a significant amount of time basking in the sun. While this basking may look like the turtle is just lounging around, it's actually important for the animal's health.

When kept as a pet, a red-eared slider needs a tank that is large enough to provide both water for swimming and an area where it can dry off and enjoy the sun. When cared for properly in the right tank environment, red-eared sliders can live a long time (over 30 years!) and be very entertaining pets.

Before You Begin

Plan on a tank size of 10 gallons of water per inch of the turtle as a general rule of thumb, with a minimum size of a 20-gallon for hatchling red-eared sliders. Keep in mind that red-eared sliders can grow to be 10 to 12 inches as adults, so it's likely that you'll eventually need a very large tank.

What You Need

Gather a few supplies to set up a tank for your red-eared slider:

  • 20-gallon aquarium or plastic container (minimum size for a young turtle, adults may need 40 gallons or larger)
  • Basking area supplies such as rocks, stones, or a plastic floating shelf
  • Heat light and ultraviolet light
  • Good quality aquarium water filter

Large plastic containers or storage tubs are good alternatives to aquariums as long as you don't mind being unable to view the turtles from the side. You won't need a lid if the container is tall enough and the basking area is positioned so that the turtles can't climb out.

Fill the Tank With Water

Red-eared sliders need an adequate amount of water in which to swim. At a minimum, the water should be about twice as deep as your turtle is long—a 4-inch turtle should have a minimum water depth of 6-8 inches.

Red-eared sliders are strong swimmers, so you don't need to worry about drowning as long as the turtle can get out of the water and there is no place it can get trapped underwater.

Create a Basking Area

The basking area for your turtle can be provided by stacking smooth rocks and sloping large smooth gravel to one side to make a land area. You could also use wood or a plastic "turtle dock." Whatever you choose to construct a basking spot, make sure your turtle can climb onto it easily and that it allows your turtle to completely dry off.

Add Tank Decorations

When designing a tank, it's a good idea to keep it uncluttered and easy to clean. Remember that turtles can knock things over and push stuff around. Plants may be a nice aesthetic touch, but turtles are likely to make a snack of them or uproot them. Plastic plants will likely be dug up and just make cleaning more difficult.

The best tank accessories for a red-eared slider are larger rocks and stones, and driftwood. If using driftwood, make sure to purchase it from a pet supplies store rather than using driftwood you find on the beach. The kind sold in the store is parasite free and will not harm your turtle.

Maintain Tank Heat

The water in a red-eared slider turtle tank should be kept at about 74-78 degrees Fahrenheit, and up to 80 F for hatchlings. The daytime ambient air temperature in the tank should be between 75 and 80 degrees Fahrenheit, with a basking spot between 90 and 95 F over the land area of the tank. The basking spot lighting can be turned off at night and the air temperature can drop down to as low as 60 F.

A submersible aquarium water heater can be used to keep the water warm if necessary. Glass aquarium heaters may become damaged by large turtles and could cause a potentially lethal situation if it heats up the water up too much.

You can protect the heater so the turtles can't bump it by placing it behind something (a brick is one idea) or by fashioning some sort of cover (a piece of PVC pipe could be used). Be sure to install a good aquarium thermometer and monitor the water temperature.

Provide a reptile heat lamp over the basking area to keep your turtle warm when it gets out of the water. A reptile bulb/heat lamp in a reflective lamp can serve this purpose, but make sure there's no way the turtle can touch the light or that the light can fall into the water. Use a thermometer to check the surface of the basking site to be sure it is reaching the correct temperature. The basking light will help heat the air in the tank as well.

Install an Ultraviolet Light

In addition to the basking light for heat, provide a full spectrum reptile Ultraviolet (UVA/UVB) light. Exposure to UVA/UVB is necessary for proper calcium metabolism and also appears to have other benefits to overall health such as improving appetite. It is also nice to take your turtle out into the natural sunlight in warmer weather if you can. Just be sure it can't escape or become overheated when in the sun!

Get a proper reptile UVA/UVB bulb and follow the manufacturer's guide regarding placement of the bulb. UV rays diminish with distance from the bulb, so it's important to place the bulb where the turtle can be close to benefit best. Replace the bulb as recommended by the manufacturer, since the intensity of UV produced diminishes over time. If your turtle lives outside, this light is not necessary.

Cleaning the Tank

Between feeding and defecating, turtles are pretty messy creatures. Your turtle tank should include a good filtration system such as a power filter or canister filter to keep the water clean. Choose a filter rated for at least double the volume of water you will be filtering since turtles are such messy pets. Filtration will reduce the frequency of water changes but your turtles will still require 25 percent water changes weekly and a thorough cleaning once a month or more.

Preventing Problems During Tank Setup 

Avoiding common problems during tank setup will help your turtle stay healthy and prevent issues in the future.

  • Keep in mind that if you want to use gravel in your tank, it can make the tank harder to clean. Additionally, you must make sure the pebbles are large enough that they won't be accidentally swallowed by your red-eared slider.
  • The most common mistake when it comes to creating a habitat for your turtle is using a tank that is too small. Double check your turtle's measurements and make sure there's enough room for them in the tank. If you're unsure what size tank to purchase, err on the side of giving your pet extra space.
  • To help minimize mess, feed your turtle in a separate container to reduce the workload on the filtration system.
  • If decorating with driftwood, be aware that it can sometimes turn the water brown. In order to avoid discoloration, soak your driftwood in a separate bucket of water for several days before adding it to your turtle's tank. Adding a carbon media to your filter will also help keep the water clear, but the carbon needs to be replaced periodically, usually once a month.
If you suspect your pet is sick, call your vet immediately. For health-related questions, always consult your veterinarian, as they have examined your pet, know the pet's health history, and can make the best recommendations for your pet.