What Kind of Water?
Some experts recommend using commercially bottled spring (not distilled) water for housing
amphibians. Tap water should always be treated with dechlorinating tablets or solutin, or left standing for at least
24 hours before adding to an aquarium to allow the added chlorine to dissipate. The use of rainwater is acceptable
as long as it is checked for appropriate pH - it is often too acidic.
Pond water is best avoided - it can be contaminated with pollutants
or parasites that can be injurious to captive amphibians.
Filters
Under gravel filters work well in set ups that include gravel, since
once established they support beneficial bacteria that convert ammonia
to harmless nitrites. This type of filter can also be used in very
shallow pools, even those set up in terrestrial terrariums. They
also have the advantage of not creating strong currents, which can cause
problems for smaller species. Because debris is pulled down into
the gravel with this system the gravel will have to be cleaned (e.g. with
a gravel washer) regularly.
There are a variety of other filter types available that are also effective. Inside corner filters with external air pumps are also a good choice for smaller salamanders since they do not create strong currents and also establish the beneficial ammonia converting bacteria. Whenever a filter is changed, add some used filter material to the new to speed the colonization of the good bacteria. Some of the stronger filters such as external filters are probably best reserved for the larger species that won't be stressed by strong water currents.
Ammonia
Ammonia is a waste product excreted by amphibians (and other animals,
particularly aquatic species) that is dangerous if allowed to accumulate
in their environment. The best way to prevent accumulation of ammonia
is to use adequate filtration and replace water (not simply adding water, but draining and adding more). About 20-25% of the water
should be replaced every week or every other week (you may want to get
an ammonia test kit to see how fast ammonia levels accumulate). Even
if changing from dirty tank to clean water, do it gradually, as the shock
of changing water chemistry can be harmful even if it is an improvement
in overall water quality (never do a full water change!).
pH and Water Quality
Generally speaking, salamanders do best at a pH (measure of the acidity)
of 6.5 to 7.5, in the water and the soil. Ideally, if collecting
salamanders from the wild, measure the pH of the soil and water in the
area and match that pH in captivity. pH strips give a quick and easy
measurement, and the environment should be checked periodically as the
pH will change over time with waste production etc. If you are moving
an amphibian to a new environment with a different pH it should be done
gradually.
If a salamander is stressed due to an incorrect pH it will be restless, moving around in areas it usually does not, and eventually will become lethargic and have decreased muscle tone.