How Often Should You Use Ammonia Tablets in Aquariums?

When you set up an aquarium, you're establishing a miniature ecosystem. In nature, such a system provides its own checks and balances. An aquarium, however, has the limitation of being a closed system. Whatever you introduce -- fish, food, water, plants -- can have a dramatic effect on the creatures living in it. Ammonia is just one of many chemicals to monitor in a fish tank, and it can be lethal. Fortunately, available aquarium products can help treat ammonia.

  1. Definition

    • Ammonia is toxic to humans, too.

      Nitrogen and hydrogen atoms combine to create ammonia. In aquariums, this compound appears as either highly toxic unionized ammonia (NH3, called free ammonia) or less toxic ionized ammonia (NH4+, called ammonium ions). A combination of high temperature and pH tend to generate a higher percentage of NH3. While ammonia is 30 percent less toxic in saltwater aquariums than in freshwater ones at the same pH, the goal is always zero ammonia in the tank.

    Sources

    • Water plants shed leaves that break down into ammonia.

      Three possible sources exist for aquarium ammonia. To disinfect tap water, water companies use either chlorine or the more stable chloramine, which is chlorine bound to ammonium. Once that bond breaks, ammonia is released into the water. Organic matter -- plants, fish food and mucus from fish -- constantly decomposes in a fish tank, producing additional ammonia. And as the fish digest their food, leftover protein travels into the blood to be excreted into the water as ammonia.

    Effects

    • Fish breathe through their gills.

      Tropical fish excrete most of the ammonia through their gills, where the blood runs close enough to the surface to interchange chemicals with the water. Ammonia irritates tissue, and the gills respond by hemorrhaging, which reduces the surface area that can draw oxygen from the water. This in turn reduces the amount of ammonia the fish can excrete, creating a deadly cycle. Ammonia also reduces the blood's ability to carry oxygen. Fish react by gasping.

    Balance

    • Healthy tanks manage ammonia on their own.

      A balanced aquarium eliminates any ammonia produced by natural processes. The biological filter contains a colony of bacteria that break down toxins, and regular changes of small amounts of water boost that natural process. Any water added to the tank should be treated with a water conditioner for both ammonia and chlorine, and fish should be added gradually to avoid an ammonia spike. Increase the number of water changes if you detect signs of ammonia distress.

    Tablets

    • Package directions vary by brand.

      Pet stores carry a variety of products for treating aquarium water. One of these products is ammonia tablets, designed to eliminate any ammonia from the tank. The problem is that these tablets also starve the biological factors in the filter, interrupting the tank's ecosystem. The tank is thrown out of balance as it tries to readjust. If you do use ammonia tablets, follow the regimen on the package and monitor your fish for stress.