With their highly-permeable skins, amphibians absorb ammonia and other pollutants over a greater surface area than do fishes. Surinam Toads, Axolotls, tadpoles and other aquatic amphibians are most at risk from poor water quality, but even terrestrial species such as toads and Fire Salamanders can quickly succumb to water-borne toxins while soaking in terrarium pools. Keeping their water clean, both visibly and chemically, can be quite a challenge.
Your pet’s natural history will determine the type of filter that should be used. For example, newts and Dwarf Clawed Frogs will be stressed by fast currents, Hellbenders are extra-sensitive to water quality, many species are prone to bacterial attack in highly-oxygenated waters, and so on. Please post below if you need help in selecting a filter.
Types of Filtration
Biological filtration, wherein aerobic bacteria convert ammonia to less harmful compounds (nitrites and nitrates), is the most important of the three basic filtration processes. Ammonia enters the water via dead animals and plants, uneaten food and the occupants’ waste products. The organisms involved in the process, Nitrosomas and Nitrobacter bacteria, live on substrates that are bathed with oxygenated water (i.e. gravel, filter pads).
Aerobic bacteria starter cultures may be purchased (i.e. Nutrafin Cycle) or obtained from the filter materials in a well-established tank. Always leave a bit of old material in your filter when changing carbon or filter pads, so that aerobic bacteria will seed the new filter medium.
Suspended solids and chemicals are removed from the aquarium through mechanical and chemical filtration.
Aquatic plants will assist filters in maintaining water quality and amphibian health. Pothos, Peace Lilies and other terrestrial plants that adapt to watery environments can also be used. Please do not discount the effects of live plants…I and many others can attest that they can make a real difference.
The use of a filter does not eliminate the need for regular water changes, as ammonia will accumulate even in well-filtered enclosures.
Yes, they are largely ignored today, but I believe this to be serious error. I have used undergravel filters to successfully keep a wide range of delicate amphibians, and have included them in several of the large zoo exhibits I’ve designed.
Undergravel filters transform the entire aquarium substrate into a biological filter. Water drawn through the gravel nourishes beneficial aerobic bacteria and inhibits the growth of harmful anaerobic species. The return tubes can be cut so that even a small pool in a terrarium can be filtered.
Undergravel filters are especially useful when rearing eggs, larvae and tadpoles, because they will not injure animals with suction and strong currents. Please see this article for detailed information on their use.
Corner or Box Filters
These “old-fashioned” inside-the-tank filters are actually quite effective if powered by sufficient airflow. I maintain a number of tanks using corner filters alone. In addition to providing mechanical and chemical filtration, these filters support aerobic bacteria that assist in ammonia detoxification.
Ideally, a corner filter should have low and high intake ports, so that water will be pulled from the very bottom of the tank and at a slightly higher level I recommend the Lee Triple Flow; most others lack low intakes. As a corner filters outflow is directed upwards, strong currents that might disturb eggs, larvae or weak-swimmers are avoided.
Corner filters can be easily hidden with plants. Live Java Moss is ideal for this purpose.
Sponge filters provide mechanical and biological filtration, and are ideal for use with amphibian eggs and larvae, and delicate specimens. They work well with African Clawed Frog tadpoles and other filter-feeders, as minute food particles are not rapidly removed from the water. This is also a consideration when salamander larvae are being reared, as many feed upon Daphnia, brine shrimp and other tiny creatures that may be pulled into more powerful filters.
The filter should be periodically cleaned by rinsing it in cool water (hot water will kill beneficial bacteria). Chemical filtration is not provided, so regular water changes are especially important.
This powerful filter is designed with turtle-keepers in mind (please see this article for information on filtering turtle tanks). In common with fish canister filters, the Turtle Clean has ample chambers for carbon, filter pads and aerobic bacteria colonies, and is simple to clean. It is placed next to (not below) the tank, and can be used to create a waterfall effect.
Despite its size and power, the Turtle Clean Filter can operate in as little as 2 inches of water, rendering it ideal for use in terrarium ponds or in shoreline-type setups housing American Bullfrogs, Leopard Frogs and similar species.
A powerful motor enables this filter to handle the copious wastes produced by Mudpuppies, Sirens, Amphiumas, Surinam Toads and other large amphibians. However, water can also be returned to the aquarium via a spray bar, so that newts and other small amphibians can also be maintained.
The Supreme Ovation is first submersible, combined pump and filter to be marketed in the USA; my original unit operated continuously, under great strain, for approximately 20 years!
The four models currently available are extremely powerful, but are equipped with a movable outlet tube and a spray bar so that strong currents can be avoided. The largest (Model 1000) circulates 265 gallons per minute, yet is compact and easy to service.
Nearly all filters designed for use with tropical fishes can be of use to amphibian keepers. Although certain modifications may be required, many are worth investigating as a great deal of research has gone into their development.
You can check out 50+ aquarium filters options here. Please be sure to post your ideas, experiences and questions below.
NutraFin Cycle: Bacteria in a bottle
Axolotls image referenced from wikipedia and originally posted by ZeWrestler
Tadpoles image referenced from wikipedia and originally posted by MarJon