Maintaining Water Quality in Your Turtle's Habitat
One of the most important things you have to do to keep your turtle healthy and happy is keep the water in its tank clean and fresh. This isn't as easy as some people think. Turtles are messy animals, and they don't clean up their rooms no matter how many times they're told! So its up to us, their human keepers, to keep their habitats clean, fresh, and healthy.
The most important thing to remember about the water in your turtle's habitat is that turtles eat, drink, swim, defecate (poop) and urinate (pee) in the same water. That makes it get dirty very quickly. If we don't keep up with it, your turtle's water will get dirty, smelly, and unhealthy very quickly.
Luckily, it's really not very hard to keep a turtle's habitat fresh and clean if we follow some simple steps.
How to Keep the Water in Your Turtle Tank Clean
Maintaining water quality in an aquatic turtle's habitat takes only a few hours split up over the course of a week if it's done properly. Here are the most important things you need to do to maintain a healthy water environment for your aquatic turtle.
1. Use a Big Enough Tank
If your turtle's tank is too small, it will be much harder to keep clean. Turtles poop a lot, and if their tank is too small, it will get dirty a lot faster. Also, aquatic turtles like to swim, and a too-small tank won't give them enough swimming room.
One common rule of thumb is that for every inch of carapace (upper shell) length, your tank should hold approximately ten gallons of water. So if your turtle's carapace is two inches long, your habitat should hold about twenty gallons of water. If it's four inches long, the habitat should hold about forty gallons of water.
If there are more than one turtle, size your tank for the first turtle, and then add half again as much for each additional turtle.
Of course, not everyone has enough space (or money) for a tank that big. If your tank is a little smaller than what's recommended above, your turtles will probably be okay. But you'll have to work even harder to keep the tank clean. Smaller tanks are harder to keep clean than bigger ones, so try to use the biggest tank you can.
2. Get a Good Filter
Turtle tank filters have to work hard to keep the water clean because turtles are so messy. Most turtle keepers use filters made for fish tanks, which is okay, except that turtles are much messier than fish.
So if you're going to use a fish tank filter for your turtle tank, get one that's rated for at least four to five times the amount of water in your turtle's habitat.
In other words, if your turtle's habitat contains 20 gallons of water, the smallest filter you should get is one that's rated for a fish tank of 80 to 100 gallons. If your turtle tank contains 40 gallons of water, you should get a filter rated for a fish tank of at least 160 to 200 gallons.
Your filter should provide three types of filtration:
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Mechanical filtration is usually provided by a sponge, filter floss
, or other media inside the filter that traps particles by straining them out. (I personally prefer filter floss to sponges, but some keepers disagree.)
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Biological filtration may be provided by the same media (sponge or floss), or by Bio Balls
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Chemical filtration is usually provided by activated charcoal and ammonia filtering media.
"Filtration media" means the floss, sponges, charcoal, Ammo-Carb, and whatever other stuff the filter uses to clean the water. Most filtration media has to be cleaned or replaced on a regular basis. Charcoal and Ammo-Carb usually last about a month. Ceramic doughnuts and lava rock can last for months or years if rinsed regularly. Filter sponges usually need to be cleaned or replaced every week or two (or sometimes more often if your tank is too small). Filter floss is just thrown out and replaced with new floss, and this usually has to be done once every week or two in a new tank, and maybe once a month in an established tank.
Never use soap or detergent to clean reusable media like sponges. Just rinse the media in water drawn from the tank itself to retain the friendly bacteria in the media. Wash your hands afterward!
If you use filter floss, don't replace the floss and whatever else the filter uses (like charcoal) at the same time because you don't want to throw away all the friendly bacteria. (If your tank uses a substrate or has a lot of rocks in it that bacteria can attach to, then this doesn't matter as much.) Finally, if your tank uses more than one filter, wait a few days to a week between changing the media in the different filters. The exception to these rules is if your tank is already full of bad bacteria and you're starting fresh, in which case you'll just have to change everything at once and let the tank cycle all over again.
There are four basic styles of filters:
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Hang-On-Back (HOB) filters hang on the back of the tank and are commonly used for fish tanks. This kind of filter usually won't work for a turtle tank (unless the tank has a filter cutout) because the water level in a turtle tank is usually kept low, and the filter's pump will have to work too hard to draw the water up the siphon. The "AquaClear
Most HOB filters are designed for fish tanks, and turtles are much messier than fish. If you use a HOB filter, get one rated for four or five times the size of tank that you have. 
"Internal" or "submersible" filters are usually attached to the glass inside the tank using suction cups. These filters are okay for small habitats (up to 20 gallons), but are inadequate for larger ones. If you're planning to start with a small tank and raise your turtles from hatchlings, then a submersible pump is probably a good choice because they're inexpensive and easy to install in a nursery tank. But when your turtles grow and need a larger tank, you'll need a larger filter.
One submersible filter that I like is the Marineland DJ100 Duetto Internal Multi-Filter(like the one pictured on the right), which I've found to be a good filter solution for smaller tanks. The Exo Terra Flo 350 Complete Internal Filter
is another internal filter that I like. I use one as a circulation pump in the 75-gallon tank on this site's video feed.
Be very careful when installing any electrical device inside the tank. You have to be especially careful when running the wire, that it doesn't run over any sharp surfaces that may damage the insulation. (And if you're a kid, always have an adult helper whenever you're working with electrical parts of your habitat!)-
Canister filters are considered the best kind of filters for a turtle tank. They usually mount under the tank in the cabinet or stand, so they don't take up space inside the tank. Canister filters
One inexpensive canister filter I've used and have been basically happy with is the ZooMed 501 - Under-gravel filters. More about these below.
3. Clean Up the Leftovers
Excess food will quickly begin to decay and will cause the water to foul much more quickly, so clean up any leftovers quickly. Another idea is to feed your turtle in a separate tank. But remember that aquatic turtles have to be in the water to eat because most turtles can't produce saliva.
You can also use a large bucket to feed especially messy foods like fish to your turtle. If you time the feeding with a water change, you can feed the turtle in the water that you removed from the tank; and then discard the leftovers with the water when the turtle is done eating.
4. Vacuum Frequently
It's very important to vacuum your turtle habitat frequently, especially if you are using a substrate. You can use an inexpensive, siphon-type aquarium vacuum
Never start the siphon using your mouth! You'll probably get sick if you do.
5. Monitor the Chemical Levels
Turtles are not quite as sensitive to chemical changes as are fish, but you should monitor at least the water's pH, ammonia, and nitrite / nitrate levels. Water test kits
There's a lot of chemistry behind aquatic habitat water quality, which I'm not going to go into right now (although I may in the future on a separate page). For now, what it all comes down to is this: Turtle tank water should have a pH between 5.5 and 8, the chlorine and ammonia levels should be 0, the nitrite level should be 0.5 ppm (parts per million) or less (preferably zero), and the nitrate level should be 40 ppm or less.
6. Change the Water Often
Actually, if you vacuum frequently using a siphon-type vacuum and throw away the water that you siphon off, you may not have to change the water very often because you'll be doing a partial water change every time you vacuum. But even with regular vacuuming, you'll probably have to do water changes once in a while. They're easy to do: Just siphon off some water into a bucket and replace it with fresh water. Usually you replace between one-quarter and one-half of the water.
How often to change the water depends on your setup, the size of the tank, how good a filter you have, how many turtles you have, and many other factors. Basically, when the water starts getting cloudy and smelly, or the ammonia, nitrite, or nitrate levels get too high, you're past due for a water change.
7. Aerate the Water.
Turtles have lungs and breathe air like humans do, so some keepers don't bother aerating their tanks. But aeration helps keep the water healthy by discouraging the growth of anaerobic bacteria and helping to agitate the water. An inexpensive aquarium air pump
8. Move the Water Around.
If you have a large turtle tank (which you should), you can help improve the water quality in your turtle tank by moving the water around -- and the easiest way to do this is by using an aquarium circulation pump
Moving the water around helps your turtle habitat in several ways:
- It improves filtration efficiency by by causing a slight circular movement of the water, if you aim the pump properly. (You don't want too much movement, though. We're not trying to build a whirlpool bath for our turtles.)
- It helps maintain a more even temperature throughout the tank.
- It helps diffuse bacteria and oxygen throughout the tank. Oxygen is necessary for aerobic (good for your habitat) bacteria to thrive. It also discourages the growth of anaerobic (bad for your habitat) bacteria.
- It helps slow down algae growth a bit.
What I personally use instead of a circulation pump is an internal filter, like the Exo Terra Flo 350, Complete Internal Filter
Undergravel filters
Undergravel filters
Traditional UGF's worked by drawing water down through the gravel, which aided biological filtration by giving the friendly bacteria something to attach to. It seemed like a great idea. The problem was that sometimes, some of the poo and leftovers would get deep down into the substrate, clog things up, and increase the ammonia and nitrate levels.
Then someone said, "Hey! Let's try pumping the water the other way," and in doing so invented the reverse-flow UGF. The way these work is that water is pumped up through the gravel by a reverse-flow powerhead connected to the UGF. This, it was thought, would help keep the nasty stuff from settling down into the gravel. Instead, the lighter stuff would stay suspended in the water and eventually drawn into the water filter, and the heavier stuff stay on the surface to be vacuumed up.
I used to be a big believer in reverse-flow undergravel filters. But over the years, I've lost my enthusiasm for them, for several reasons. The first reason is that it's very difficult to find reasonably-priced pumps or powerheads with sufficient head pressure to make the RFUGF work properly. The second reason is that I've found that RFUGFs tend to accumulate a lot of detritus (turtle poo and other gunk) under the filter plates, even though the water pumped under the plates is filtered. Eventually, that can't help but hurt the water quality.
The long and short of it is that I no longer use undergravel filters. I know that a lot of people who are much smarter than me still believe in them, so feel free to listen to the expert of your choice and make your own decision. But I don't use them anymore.
Some Other Water Quality Ideas
In addition to the above, there are other ways to help keep your turtle's water clean. Some of these involve more work to set up, however, and each has its own advantages and disadvantages. Not everyone agrees about whether some of these things are good ideas, so do your research and make your own decisions. (I personally use all of them and have not had any problems.)
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Add a plant or two. Plants help consume pollutants and compete with algae for available carbon dioxide. But adding plants to a turtle habitat has to be done carefully. Some plants are toxic to turtles, and others will just become salad. Also, most plants need to be rooted in something, which means you'll have to use a substrate. You can read more about planted turtle habitats here. -
Add a few working fish. Some fish, like Otocinclus catfish ("Oto's") and Hypostomus plecostomus ("plecos" or "plecs"), can help keep the water clean by eating algae and scavenging for leftovers on the bottom of the tank. Others, like Danio sp. ("zebrafish") help by eating scraps that our messy turtles ignore. But working in a turtle tank is a dangerous job for a fish because your turtle may eat them! So unless you're willing to take a chance that your working fish may become turtle food, don't add them to the tank.
Be careful about which fish you add: Otos, plecos, and zebrafish are probably the safest. They're also pretty fast swimmers, so they may be able to out-swim your turtles -- for a while, at least -- and avoid becoming lunch. It's important to avoid fish that could injure your turtles, such as armored catfish. Finally, remember that you must aerate your tank if you're going to introduce fish, or else the fish will suffocate and die. Order live fish today from Big Al's Online with an Arrive Alive Policy and Save 25% with code Save25. -
Introduce friendly bacteria. Pet supply stores sell tablets that can be dropped into a new fish tank to "condition" the water by removing chlorine, and sometimes chloramine and ammonia. Some of these conditioners also contain starter cultures of beneficial bacteria, and they aren't a horrible idea when setting up a new tank. If you choose to use them, drop them into the tank at the dosage on the label after it's set up and the filter is running, but a day or two before you introduce the turtles. They may cause the water to get cloudy at first when the bacteria "bloom," but this is harmless and clears up on its own in a few days.
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Water additives like Turtle Clean
