The biggest part of any aquatic setup for spotted turtles is the nitrogen cycle, which includes the same principles that freshwater aquarists may already understand intuitively. Turtles release ammonia when they defecate, which is toxic. The nitrogen cycle changes ammonia into nitrite, which is also toxic. Later, it changes nitrite into nitrate, which is not toxic in moderate amounts. Nitrate becomes toxic when it accumulates in large amounts, but if the water is changed on a regular basis, this removes nitrate and keeps the water quality safe. Some owners prefer to use chemical additives to help manage spikes.
Starting off, the nitrogen cycle is slow to develop, but using a bacterial supplement can help jump-start the beneficial bacterial colony that runs the cycle. Most new tanks are unstable for a few weeks, but become more stable when they have been running for a few months. Water changes need to be done more often in the first weeks, which helps remove ammonia as the turtle produces it while the tank is adjusting to the bioload of the turtle and its waste. Using an ammonia detoxifier to deal with sudden spikes can help prevent the turtle from suffering ammonia toxicity during these early weeks. Spotted turtles that suffer from ammonia burns will usually have red mucous membranes and may struggle to breathe.
Using a test kit will help verify that everything is going the way it should during the nitrogen cycle, especially in the early weeks. A stable tank should have an ammonia reading of 0 ppm, a nitrite reading of 0 ppm and a nitrate reading of 5 to 50 ppm. In new tanks, these readings may vary until the cycle stabilizes itself. Readings above 0 ppm ammonia or nitrite require fast water changes to prevent ammonia poisoning.
After the cycle stabilizes itself, owners should familiarize themselves with a basic care routine to maintain the cycle and prevent spikes from occurring. This usually includes a regular water change, which will remove nitrates from the water. It will also include water tests on a period basis, which will help reflect the parameters and let the owner know if the tank needs attention. Occasional bacterial supplemental dosing will keep the bacterial colony thriving and ensure that the cycle does not experience too many sudden spikes or issues. Maintaining a good care routine for the filtration of the tank can help keep spotted turtles healthy and thriving in their habitat over the long-term.