One effective setup for aquatic turtles in small tanks

Over the decades, I have used a great variety of cleaning methods and filtration systems. Aquatic turtles were often very hardy and good pets, but keeping their water clean was always a terrible chore. Turtles produce more waste than fish. Filters were always a disappointment, and I'd resort to changing the water-- siphoning and carrying bucket loads-- once a week. The internet changed all that.

When I first got online, I joined the only turtle discussion list that existed at the time and found a wonderful community with a wealth of knowledge. Several of the people there used a system that was highly regarded for its water quality and ease of maintenance. As soon as I started using it, my attitude toward aquatics changed instantly. They are very easy and a joy to keep.

The overall system that I use now involves a canister filter-- the Magnum 350 Deluxe model-- used along with an undergravel filter plate. (I recommended Undertow UGFs.) After decades of vacuuming and constant water changes, this new idea seemed worth a try. But, of course, I didn't want to risk leaving my turtles in bad water, (even if it looked clean). So when I got my first Magnum/undergravel filter going, I tested the water frequently. The results were exactly as those helpful people had told me-- fabulous! I also noticed very soon that I never had problems with algae with this system. Ease of maintenance is unparalleled.

The basic concept: Using a good canister attached to an undergravel filter plate with a thick layer (3" or more) of gravel on top creates a complete, natural system to clean water. The gravel layer filters the water biologically. You can stir it up once in awhile if you want to, but it really doesn't need much tending, because the turtles naturally turn it over in their travels about the tank. The waste is pulled down through this natural filter, breaking it down into small particles, which are sucked up into the canister. The sponge prefilter removes that stuff, providing mechanical filtration. Then the water travels through a charcoal center, which chemically cleans it. The end product of this 3-step process is terrific.

The setup: You can set it up anyway you want, by connecting the canister to one of the up-tubes of the undergravel filter. (You cover the other openings with the caps provided.) Then the output hose of the canister can be placed anywhere you want. I like to put it on the opposite end of the tank, for maximum circulation. I also like to add a little basket of charcoal to the output hose. I'm not sure if it comes with the canister, or if I've found these from other filters that are lying around, no longer being used. You can place the output hose so it produces a little waterfall, or put it in the water for silence. I don't really have any two aquariums set up exactly the same. I just jury-rig things together and turn it on. There is great flexibility in how you can configure it, so just experiment. (Ignore the instruction manual, which shows only one setup, with the hoses right next to each other.)

Maintenance: To maintain the system, you rinse out the canister's prefilter every week or two. You can see it gathering "stuff" and clean it as it gets dirty, because the canister is transparent. The charcoal can be replaced every month or so. If you use real charcoal, you can clean it and heat it up, which will "recharge" it and make it useful longer. Frankly, it's just easier to replace, and not terribly expensive. Or you can use some of the mixed materials that are available in aquarium stores. In addition to tending the canister, you need to add water to replace that which evaporates. Exchanging water is not necessary. I know there are people who don't believe this, some of whom are quite experienced with other types of filtration systems. I didn't believe it either, which is why I tested the whole concept carefully before giving up on water exchanges. It works great. Major cleanings, where you vacuum the gravel, remove the water and scrub everything, are necessary only once or twice a year, depending on how well you tended the filter, how many turtles, etc.

Additional benefits: I use lots of aquatic plants because these provide some of the best nutrition possible for aquatic turtles. Other filters clog up with bits of plants. Since this system pulls the plant bits downward, to be naturally broken up in the gravel, there is never a problem with clogging. Also, because the suction pulls everything down through a large surface area, there is no "hot spot" of suction to entrap small turtles, so it's an ideal setup for weak or tiny turtles. Of course, you have to be careful that your uptake hose is firmly connected to the UG filter plate. If it gets loose, it would act like other canister filters, and create an area of powerful suction.

Disadvantages: I have heard that the Magnum canister doesn't work well with sand substrate, so the whole thing might not be best for people with softshell turtles who use that substrate. I've also heard that the vacuum that comes with the Pro model is too powerful, and gravel is sucked up into the canister, where it can damage the impeller. Don't bother to buy it, and don't use it; you don't need it anyway. There are inexpensive, self-starting siphons that do a good job, when you want to vacuum the gravel. I can only vouch for the Magnum 350 Deluxe (using the media cartridge, not the water polisher) with this system, because I have no experience with Fluvals or Filstars or other brands. They might work fine, but I can't say that. If your tap water is "hard" or contains lots of added chemicals, you might want to use bottled water. Otherwise, as water evaporates and you add more, any minerals or chemicals in the water would concentrate. I can't recommend the Magnum H.O.T. models with the UG filter, because it works best with full tanks. With turtles rather than fish, we usually don't keep the tanks full enough. I have one, and used it for a few years, but it was a bit of a pain to restart with half-full tanks. I can only recommend the system for tanks under 75 gals. Above that, you would probably want to add an additional filter, perhaps two Magnum/UGF setups in one tank. If you use too little gravel, there may be times when a portion of the UGF plate is exposed. The biological component of the system will not function then. However, the normal high and low points of gravel that naturally develop and change as the turtle moves about the tank seem to have no effect-- the system continues to work fine. It's also important to know that the canister must be lower than the water level to work correctly. With a raised tank on any kind of stand, you can place the canister on the floor. If your tank is on the floor, the canister might not work correctly.

The gravel issue: Some turtle keepers have concerns about using gravel. They have heard the myth that it kills turtles. In fact, we know from research with wild turtles, that they eat gravel in the wild and it doesn't harm them. It may serve some purpose in digestion, but that is not established. What we do know is that small pieces of gravel pass harmlessly through the digestive tract. Since there is no way for small gravel bits to bind together, forming a large mass, it cannot cause an obstruction. Larger rocks can cause problems, especially if there is no gravel available. In their quest for gravel, some turtles will desperately try to eat larger rocks, and those do pose a risk. Another concern that is often expressed about gravel is that it gathers "gunk" and leads to poor water quality. That would be true in a system that does not use an undergravel filter plate. If you use gravel, you *must* use a UGF plate too, and vice versa.

Summary: I have been keeping turtles for over 40 years, and have never found an easier system to maintain, or one that produced water of this high quality in relatively small tanks. It's such a joy to never have to deal with excess algae, or shell rot, or any of the other common effects of poor water quality. I've been delighted to say goodbye to hauling water back and forth. This is the way to go if you want excellent water quality, but don't want to have to work hard. The people who first discussed this on that old internet list no longer seem to be active in the online turtle community, but I wish there was some way to thank them. My life improved tremendously when I started using this system.

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 © 2005 Mary Hopson, Anchorage, AK
This information sheet may be freely copied and distributed.