Red-eared sliders are tiny, quarter-sized turtles as babies, but quickly grow into large, 12 to 16-inch adults. They require extremely large aquariums, substantial filtration and ample lighting. A red-eared slider's tank setup is the key to its health, and a well-functioning tank or pond ecosystem will ensure a long and happy life for these hardy turtles.
Select an appropriately sized aquarium or pond. For every inch of turtle, you must have at least 10 gallons of water. This means if you have four four-inch turtles, you have 16 total inches and will need 160 gallons of water. Turtles grow rapidly and will fight or become sick if they are overcrowded. Therefore, it's a wise investment to buy an enclosure that will be sufficiently large for your turtles when they are full grown. For a single turtle, this will mean a 120 to 140-gallon tank.
Choose a substrate for the tank. Turtles enjoy digging in the bottom of their enclosure, and a substrate can help trap debris, maintain proper pH and help the water remain clean. However, red-eared sliders will eat anything they can fit into their mouths and will choke on small, artificial gravel. Large river rocks are an ideal choice for substrate. If you don't use river rocks, choose a clean, debris-free substrate that your turtles cannot fit into their mouths.
Establish proper filtration and clean water. Red-eared sliders are very messy and frequently require double filtration. This means that for a 100-gallon tank, you should plan on buying a filter that is sufficient to filter 200 gallons of water. Dechlorinate the water you add to your tank using a water dechlorinator. Follow the instructions on the package.
Provide your turtles with a basking area. Red-eared sliders spend a significant portion of their time out of water, and must be able to completely dry off. Consequently, the more land you can give your turtles, the happier they will be. For small turtles, a floating island or piece of wood is sufficient. For larger turtles, you may need to build a rocky land area or cut wood and attach it to the side of the aquarium or pond. The land area should support your turtle's weight and should allow your turtle to become completely dry.
Provide your turtles with 12 hours per day of UV lighting. If your turtles live outside in a pond, you do not need to add a lamp. If they are kept inside in an aquarium a UVA/UVB bulb can provide them with artificial sunlight. Without UV light, red-eared sliders cannot properly metabolize calcium, and can develop life-threatening metabolic bone disease.
Ensure the water temperature is appropriate for your turtles. Red-eared sliders require a water temperature slightly above room temperature, ranging from 74 to 85 degrees Fahrenheit. An aquarium heater or over-the-tank heat light can raise the temperature to the proper levels. Monitor the temperature frequently to ensure it is not too hot or too cold. At temperatures below 70 degrees, turtles become lethargic, and at temperatures below 65 degrees, they stop eating.