Pet Chinese water dragons live in a very wet environment. Their enclosures should consist primarily of water that they can swim in with branches and rocks to climb on about the water line. Keeping this large amount of water clean can be a challenge but should be a priority to all water dragon owners.
The easiest way to keep your water dragon water clean is to invest in a quality water filter. Any filter that will operate without the entire tank being filled with water will do but some types and brands work better than others.
Undergravel filters used to be the way to go before other types of filters took over the market. Undergravel filters worked well if you use gravel and regularly mix the gravel up to allow the debris to drop to the bottom of the tank where the filter lies. It is basically a plastic screen that the gravel sits on. The screen allows the waste matter to drop to the bottom of the tank and the debris is then directed through a plastic tube (or several tubes) up the back of the tank and into a small filter cartridge via suction.
Canister filters are now the filters of choice due to their efficiency and extra cleaning power. These filters have tubes that suck up the dirty water and the canister part of the filter sits outside the tank collecting the dirty water and filtering clean water back into the tank. You can adjust the height of the tubing that collects the water making these filters work well for water dragon tanks. Canister filters are pricey but well worth the investment since they typically take the dirty water through several stages of filtration before returning it to the tank.
Submersible filters are another option for keeping water dragon water clean. These filters are single piece units that are completely submersible. These are nice for smaller set ups or work well in a larger tank if multiple filters are used.
You shouldn't have to do water changes very often if your filters are working well. But when the occasionally change is needed, make sure you never change 100% of the water. 50% or 75% water changes are preferred. Complete water changes should only be done after you test the water with a test kit and find that the ammonia, nitrites, or nitrates are too high.
Water Temperature and Aeration
Aerating the water in your water dragon tank is not a problem when you have a filter. The filter will naturally aerate the water when the clean water pours back into the tank. But the filter does nothing to maintain water temperature. Submersible water heaters are available with thermostats to control water temperature. They can help maintain warm waters for your water dragon.
Water dragons, along with all other exotic pets, need to have the chlorine removed from their water. Chlorine is found in all tap water and will naturally dissipate if left sitting out for 24 hours. To speed up the chlorine removal process special water additives are available from the pet shop. De-Chlor and Prime are two brands that are available in the fish section.
Amount of Water
Your water dragon should be able to be fully submersed in water, or preferably, able to dive into his water. This amount of water is not only natural to your dragon but also helps provide the 80% humidity they need.
By keeping your water clean you will decrease the likelihood of your water dragon getting ear infections, burdened with parasites, or have dysecdysis. If you are having problems with the health of your water dragon, try testing the water quality and call your exotics vet.