Avoid gravel or sand substrates because they make cleaning much more difficult. If more elaborate enclosures are set up with substrates, they should have filtration, bottom drainage and low stocking densities. Water Quality Clean water is crucial to good health and the best way to assure this is through frequent full water changes. Partial water changes are not acceptable. Several factors determine how often the water should be cleaned.
Smaller volumes require more frequent water changes.
For instance, for 3 or less - 4 inch turtles, a 10 gallon aquarium would need to be changed 2 to 3 times per week and a 50 gallon aquarium would need to be changed once a week. Thus, the larger the volume of water, the less frequently it needs to be changed. Obviously, stocking density will dramatically affect this. The more turtles in the cage, the more frequently the water must be changed even with very large volumes. Feeding frequency also affects water quality.