You've selected your aquarium and decorated it, but don't "just add water." Follow these precautions to ensure a healthy environment for your pets and avoid potentially deadly conditions.

Dechlorinate the Water

Your tap water is treated with chlorine or chloramines (nitrogen and chlorine compounds) to kill such bacterial contaminants as E. coli. But these chemicals can also kill your fish, so you must remove them before turning your finny friends loose in their tank.

You can remove the chlorine and chloramines from the water with a standard chemical dechlorinator or by passing the water through activated carbon. A test kit will tell you when the chemicals are gone. Use extra caution when setting up a new tank because inactivated chloramines (not chlorine) can release ammonia. Tanks with established filtration systems can quickly convert ammonia to a harmless nitrate molecule, but new tanks can't handle the workload.

Some additives on the market can remove chlorine, chloramines and ammonia from water. Or you can trickle water through zeolite or other ammonia-absorbing mediums. Consult with your local aquatic specialist for advice.

Encourage Nitrifying Bacteria

Naturally occurring nitrifying bacteria are the worker bees of the aquarium. Without them all inhabitants would perish from organic pollution. Unfortunately, they are also probably the least understood inhabitants of the aquatic ecosystem.

In a nutshell, these bacteria convert the toxic by-products of decaying organic material into the nontoxic nitrates that plants use to grow.

Biological filters provide lots of living space for these helpful bacteria, allowing them to break down waste. But an overpopulation of fish overworks these microorganisms and prevents them from adequately detoxifying the environment. The resulting buildup of toxins such as ammonia and nitrites can stress your fish, weaken their immune systems and lead to disease outbreaks. So take care not to crowd your aquarium.

Adjust the pH

"Normal" water pH varies depending on where you live, but the scale measures pH levels from 1 to 14 with 7 being the neutral pH level. The pH levels in your aquarium should match the pH levels required by the fish in your aquarium, as there are differences among species. You probably didn't know that the very water your pet needs to survive could be so fraught with dangers. But following these guidelines will help you keep your swimmers healthy and active.