Red Eared Slider Turtle Habitat and Red Eared Slider Turtle Tank Size
You should plan on having 10 gallons of water per inch of turtle as a general rule of thumb but a 20 gallon tank is a minimum size for hatchling red eared sliders.
Keeping in mind that red eared sliders can read 10-12 inches as adults, you can see that eventually you will need a very large tank. Large plastic containers or storage tubs are good alternatives to aquariums as long as you don’t mind not being able to view the turtles from the side. As long as the container is tall enough and the basking area is positioned so that the turtles can’t climb out of it you won’t need a lid.
The basking area for your turtle can be provided by stacking smooth rocks, sloping smooth, large gravel to one side to make a land area, using 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
The water in a red eared slider turtle tank should be kept at 75-78 degrees Fahrenheit (23-26 degrees Celsius), and 78-80 degrees Fahrenheit (26-27 degrees Celsius) for hatchlings.