How to keep turtle tank water clear

How to keep turtle tank water clear

Red-eared toads and other aquatic turtles spend a lot of time in the water. Pure water is therefore essential. Of course, turtles defecate in their water as well, so maintaining good water quality can be a challenge. Cloudy, smelly water in a turtle tank is a common problem, but even water that looks clean can contain wastes, such as ammonia and nitrites, which can reach harmful levels. Therefore, maintaining good water quality is an important aspect of turtle health.

Water quality

Although turtles are generally not as sensitive to water quality issues as fish, treat turtle tanks the same as fish tanks. When the waste in the tank decomposes, ammonia is released which is potentially toxic and can irritate turtles, even in low concentrations. As a reservoir becomes established, beneficial bacteria grow in the reservoir and filter out; some bacteria break down ammonia into nitrites (also toxic) transformed by other bacteria into less harmful nitrates. However, before this “nitrogen cycle” takes hold (or if it is disrupted in an old tank), the levels of harmful byproducts or the bacteria that use them may increase.

Measure water quality

Pet stores offer ammonia, nitrate and nitrite test kits. Monitoring these levels can help you spot conditions in the tank that may be irritating or harmful to your turtles. Check with the pet store and follow the instructions that came with the kits. The instructions will also contain information on the safe and hazardous concentrations of each chemical. If the levels of ammonia, nitrates, or nitrites are too high, change the water completely. If you see moderate or gradual levels, perform more frequent partial water changes (or a complete change).

PH (a measure of acidity) is not as critical as waste, but measuring pH is also a good idea. Typically, red-eared sliders are pretty tolerant of small changes in pH, but if you take this into account, they can alert you to changes in the chemistry of your turtle’s water. The pH should be between 6 and 8 for red ear sliders. Pet store products allow you to safely lower or raise the pH if necessary.

What about chlorine in water

Opinions differ as to the advisability of de-chlorinating tap water for turtles. Turtles may not be as sensitive to chlorine as fish or amphibians, but it can still irritate them (especially their eyes). Chlorinated water can also destroy beneficial bacteria in the tank, affecting the nitrogen cycle and waste degradation. It is therefore ideal to de-chlorinate the water — the easiest way is to use water conditioners available at pet stores.

Some cities use chloramine in addition to chlorine to treat tap water. If it is so, find a water conditioner labeled to remove chlorine, chloramine, and ammonia (a byproduct of chloramine deactivation). The chlorine will dissipate after about 24 hours, but the chloramine will not.

Salmonella warning

Be aware of the risks associated with salmonella and take appropriate precautions when changing water, cleaning filters or other accessories in the turtle tank, and handling your turtles.

Tank size: Bigger the better

Water quality and cleanliness are easier to maintain in a larger tank. In a smaller amount of water, the waste is more concentrated. With a larger tank, wastes and their byproducts are diluted. In a large tank, partial water changes are more convenient for maintaining constant water quality, rather than having to change much (or all) of the water in a smaller tank. An oft-cited general guideline is 10 gallons per inch of turtle.


There are several options for filters. When it comes to turtles, choose a filter rated at two or three times the size of your turtle tank. For example, if you have a 20 gallon tank, choose a 60 gallon filter, even if the tank is not full. Filters with several different levels to remove waste as well as byproducts are recommended (mechanical, biological and chemical filtration). The subject of filters can seem complicated and intimidating — the Types of Filters and Filtration sites cover the pros and cons of different filtration methods, as well as tips for optimizing the benefits of filters.

Partial water changes

Regularly remove some of the water and replace it with fresh water. This removes and dilutes the waste. The frequency of partial changes and the amount of water to change will depend on factors such as the size of your turtle, the size of the tank, the filter and whether you are feeding the tank. However, frequent partial water changes (weekly or maybe two to three times a week if necessary) will go a long way in maintaining water quality. Using a gravel vacuum or siphon to remove the water makes this job much easier, but never prime a siphon through your mouth due to the risk of salmonella contamination.

Pass the substrate

Keeping the bottom of the tank bare makes cleanup easier since waste and uneaten food cannot get stuck in rocks. Rocks or coarse gravel (too large to ingest) at the bottom of a tank can be attractive but is not necessary.

Feed out of the tank

One way to cut down on the amount of waste you have to deal with in the tank is to feed your turtle in a separate container, although that’s a matter of choice. Try a small plastic tub or storage container. Using water from the tank is an easy way to make sure the water temperature is hot enough. Just replace the water taken for feeding with fresh water (and you have made a partial water change with each feeding). This eliminates the problem of excess rotting food in the tank, and turtles often go to the bathroom soon after eating, so the amount of turtle waste accumulating in the tank is also reduced. Next,

However, this is a lot of extra work and the extra handling can be stressful. You can choose a separate feed tray for messier or higher protein meals and feed other less messy foods, such as greens and veggies. Many owners also decide to feed the tank which is good, especially with a good filtration, water renewal and monitoring system. Collecting excess food particles and water changes soon after feeding can also help if you are filling the tank.

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