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A Filter Design for Box Turtles

By Suzanne O'Leary

     When one of my American box turtles kept getting ear abscesses, my vet said that I must fit a filter in her water dish. Filtering shallow water is not easy, but after a lot of trial and error (mainly error) I finally made this filter which works in 3 inches of water, and though I'm sure it could do with some refinements, there have been no ear abscesses since I installed it, just over a year ago. The filter removes impurities from the water by drawing it, via a power head (a kind of pump), through a box of activated carbon and ammonia remover. This is the filter in its original Heath-Robinson form, assembled frantically before another ear abscess could erupt.

What you need to build the filter:

  • 1 x large cat litter tray
  • 1 x Aquaclear 201 power head (or alternative)
  • 1 x Plastic Ferrero Rocher chocolate box (the rectangular kind, approx. 14.5 x 7.7 x 7.2cm) or alternative
  • 1 x Rena (or alternative) under gravel filter plate (the kind which slot together)
  • 1 x strainer (spare part for Eheim 2007 sponge filter)
  • 1 x 3/4" hose union washer (spare part for washing machines)
  • Activated carbon which sinks (e.g. Crystal Clear, Interpet, King British,Supa)
  • Zeolite (ammonia remover)
  • Two adhesive hooks

         I chose an Aquaclear 201 power head because it can be mounted on its side, has adjustable flow, and is fairly narrow in width - ideal for shallow water. The body of the filter is the plastic box. A hole is drilled in one end to insert the inlet of the power head. Part of the front of the box is cut away, and a cut down Rena under gravel filter plate inserted to let water in and to stop the filter material spilling out. The strainer has the narrow end blocked off with a piece of plastic or cork to prevent filter material getting sucked into the pump. The join between the power head and the body of the filter is sealed with the 3/4" hose union washer, which also keeps the power hjead attached to the filter box. Once all this is assembled, the plastic box is filled with approximately 13/4" - 2" of activated carbon mixed with a generous sprinkling of zeolite; enough filter material to cover the strainer, but still be below water level. The activated carbon and zeolite can be obtained from good pet shops and aquatic stores. They have to be rinsed before use to get rid of any dust. I use activated carbon as it's more efficient at removing impurities than ordinary filter charcoal.

         The water dish itself is a large cat tray with slightly sloping sides, though a tray with vertical sides would be ideal to mount the filter on, the ones I have seen are not deep enough to submerge the pump, which has to be below water level or it will overheat. A piece of sloping rock in one corner of the cat tray helps the turtles climb in and out of the water, though they more often climb over the filter. Two adhesive hooks, butted up against the filter box and stuck to the floor of the cat tray, help to prevent the turtles from dislodging the filter.

    Day to day running      I use coconut peat as the substrate in my box turtle vivarium, so every day I check the filter box, and remove any build up of peat and/or droppings from it. Every two to three days, I empty the contents of the filter into a plastic colander and rinse them with clean water, and renew the water in the cat tray. In a vivarium with fewer turtles (there are four in mine), and a different substrate, such as bark chippings, the filter probably wouldn't have to be cleaned out so often. Every weekend I scrub the cat tray, filter box and strainer out with a full strength solution of Tamodine E (sterilising fluid would do just as well) rinse them, and clean out the power head using just plain water (the Tamodine E or sterilising fluid might damage the metal parts) and pump head brushes (available from good pet and aquatic stores). I renew the carbon and zeolite about once a month.