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Nitrates, Nitrites and Amonia
The pH and dH measure are not the only chemical measures that are important in an aquarium. Chemicals can enter the water through the fish, themselves. The most important of these chemicals is likely to be the ammonia related chemicals. The so-called ammonia cycle starts with the very aquarium inhabitants that the fish keeper seeks to protect – the fish. Every fish give off ammonia from breathing and in their waste outputs. Ammonia also comes from decaying plants, uneaten food, and dirty filters that do not work very well. The more fish, dead plants, and uneaten food, the faster ammonia (NH3) enters the water.
When ammonia enters the water it is broken down by bacteria into nitrites (NO2–). However, this takes time and requires that the correct bacteria is in the tank. That bacteria comes naturally, but it takes time to establish itself in the aquarium. This process is known as “cycling” a new tank.
The amount of ammonia tolerable in the aquarium is basically 0. However, up to 1 part per million (ppm) can be tolerated by many fish. In general lethality for fish begins at 1 ppm. Keeping that concentration down to tolerable levels requires:
- Regular water changes. Since ammonia is uniformly distributed in the water, replacing X% of the water will remove that same percentage of the ammonia in the water. Weekly water changes of 20% – 50% of the water can help to keep ammonia, and down steam chemicals based on the reduction of ammonia, in check.
- Keeping the number of fish in the aquarium to a tolerable level (see the article on this subject on the web site)
- Avoid over feeding fish. Never feed the fish more than they can eat in 4 – 5 minutes. Feed small amounts each day.
- Keep dead fish and plants out of the water.
Signs of ammonia poisoning in fish are fish gasping for air at the surface of the water, red gills, and death from internal hemorrhaging.
Next, the resulting nitrites are broken down by other bacteria into nitrates (NO-). Unfortunately, nitrites are also dangerous to fish. When the concentration of nitrites gets to be too high the fish can literally suffrocate in the water. When the concentration of nitrites exceeds about .29 ppm death begins for most species. But up until that point the symptions are closely related to those of ammonia poisoning. In addition, the symptoms of nitrite poisoning are listlisness of the fish, rapid gilling, and brown gills. Fortunately, water changes can have the same affect as for ammonia poisoning.
Fish are generally much more tolarent of nitrates than either nitrites or ammonia. The ideal range for nitrates are under 10 ppm. At 20 ppm the nitrate concentration begins to be high, with letal results beginning at about 100 ppm. One major indication of nitrate problems is a sudden bloom of algae in the tank.
The best way to treat all of these conditions are:
- Remove the cause of the condition. This may be too many fish or overfeeding. Certainly, removing any dead fish, plants, or old food is indicated. Decaying matter pushes ammonia levels up, along with the downstream nitrites and nitrates.
- Clean the filters. Filters need to be cleaned off or changed regularly to remove potential sources of chemicals being returned to the aquarium.
- Immediate water changes of at least 20%. A larger change of up to 50% is better, if the fish will tolerate it. Water changes should be made no more than every other day if chemicals are not used to age the water. Weekly water changes should be done as regular maintenance.
- Regular testing of each of these quantities should also be done.
Maintaining the correct levels of ammonia, nitrites, and nitrates is an important part of keeping fish healthy and happy.