Overwintering Tropical Aquatic Turtles

A Gulf Coast Turtle and Tortoise Society Care Sheet

Introduction

Turtles that come from the tropics (roughly between the Tropic of Cancer and the Tropic of Capricorn), usually do not hibernate in their natural environment.

These turtles can be kept outdoors during most of the year in the non-tropical regions of the world, but may need to be overwintered indoors during the colder months.

This Care Sheet is intended to give some suggestions about how to overwinter aquatic turtles.

Containers

For very small turtles, you can use a MacCourt AT2606 mixing tub (26" x 20" x 6" deep). These are sold by Home Depot and others. The following pictures show two of these set up for aquatic turtles and a close up of one of the occupants.

For small to moderate sized turtles, say with carapace SL lengths of less than 7 inches, a 24" x 36" x 8" mixing tub, for example a MacCourt Super Tub, can make an inexpensive container. These are available on the Net (search for MacCourt ST3608) for around $25.00. They used to be carried by Home Depot, but the last time I looked, they were not.

A larger tub, 60" x 36" x 12", is also available from the same manufacturer as model MB6012. These are more expensive, being available for around $100.00.

Feed stores often have tough plastic tubs in various sizes. These can be fairly inexpensive, for example I recently purchased one that was 40 gallons (outside dimensions of 41" x 30" x 14" deep) for less than $25.00. These are available on the net at Tuff Stuff.

Undergravel Filter

Whichever container is used, adequate filtration is required to maintain good water quality. Obtain a good undergravel filter plate (for example, from Perfecto Manufacturing) that covers at least half of the tub bottom.

An undergravel filter is a slatted tray which forms a false floor that allows a layer of gravel to be suspended above it so that water can be circulated down through the gravel. One or more vertical tubes are attached to the plate and water is drawn up through these tubes using a powerhead submersible pump that is placed at the top of the tube. Note that airstones are sometimes used to power an undergravel filter in tropical fish tanks but they are completely inadequate for use with turtles.

The suction created by the powerhead pulls water and wastes down through the gravel and provides a source of oxygenated water. Beneficial nitrifying bacteria (see: Behavior and Physiology of Nitrifying Bacteria), which require oxygenated water to grow, help break down the waste and keep the water clean. The gravel bed above the undergravel filter tray is the filter medium and this filter functions both mechanically, by trapping debris, and biologically, by acting as a colonisation site for the bacteria that break down the waste. Note that it may take a few days for a bacterial colony to establish. It is important to always have the powerhead operating so that the bacteria have a constant supply of oxygen.

Purchase a powerhead that will circulate the volume of water in the container at least five times an hour. For example, I have a setup using a 40 gallon tub that is about half full (20 gallons of water). The power head used, a small one, is rated at 120 gallons per hour so the turnover is 6 times per hour.

Most uplift tubes are sized for use in an aquarium. These will need to be cut as short as possible so that the powerhead can be at least partially submerged when placed on the tube:

At least the impeller section and the discharge from the pump needs to be under the surface of the water in the container. This can present a challenge with the shallow (6 in) container mentioned above, but it can be done with a small powerhead and a very short uplift tube.

Select a gravel that is fairly fine but large enough so that it does not fall through the openings in the under gravel filter plate. Blasting sand comes in different sizes and may be an economical source for your gravel. You should have at least 2" of gravel bed for good filtration. This may be difficult to achieve with the smallest containers, but put as much gravel as you can get away with without allowing it to enter the top of the uplift tube.

The gravel will need to be throughly washed before it is used. Do this outside. Take a 5 gallon bucket and fill it about 1/3 to 1/2 with unwashed gravel. Run a hose into the bucket and swish the gravel by hand. While the dirt is suspended, tilt the bucket to empty as much of the dirty water as you can without losing any gravel. Repeat this swish and tilt operation with the hose running until the gravel is clean.

Putting it all together

Put the filter plate on the bottom of the tub and pour the cleaned gravel over it. The weight of the gravel will hold the plate in place. Be careful not to lift the plate as you don't want gravel under the false bottom. Cover the plate as described above, being careful to not get it above the top of the short uplift tube.

Fill the tub with fresh water to the level where you can cover part of the powerhead. Place the powerhead on the top of the uplift tube and plug it in. If the powerhead is sized correctly, there will be a nice gentle circulation in the tub without being excessive. Congratulations - you have just constructed an effective filter for your overwintering turtles!

Cleaning the Under Gravel Filter

You will need to occasionally clean the filter's gravel bed to maintain the highest water quality. This is easily accomplished with a gravel cleaner that can be obtained at a tropical fish supply store. This is usually done by siphoning the water through the gravel cleaner into a bucket. It will be much easier if you can arrange to have a hose putting water into your tub and have the gravel cleaner hose discharge outside so you can do a through job without having to interrupt the process to add water and empty the bucket.

Copyright (c) 2004 Gulf Coast Turtle and Tortoise Society
Permission is granted to copy for non-profit use with proper credit given. For any other use you must obtain permission.

Gulf Coast Turtle and Tortoise Society
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Houston, TX 77073
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