Water for Aquariums

Impact of Water

• Chlorine and Chloramine
  Chlorine is highly toxic to fish even at levels as low as 0.1 ppm. Chloramine is even more toxic than chlorine because it is more stable in water. Chloramine penetrates in the blood of fish and binds to the iron of the hemoglobin in red blood cells, causing a reduction in the cells capacity to carry oxygen. Activated Carbon, placed up-stream of the reverse osmosis membrane of water purification systems is known to remove efficiently these oxidizing agents. 

• Ammonia, Nitrites, Nitrates, Phosphate
  Ammonia is toxic in both freshwater and saltwater tanks. Its toxicity increases with temperature and pH. Even low levels of ammonia can stress fish and make them vulnerable to diseases. Nitrite is not as toxic as ammonia, but can stress the fish as well. Nitrite may not have readily visible effects but it interferes with the oxygen metabolism and can affect the physiology of the fish (and therefore research results). Nitrate is less toxic than ammonia and nitrite, but it can also cause stress in fish and should be kept at a low level. Phosphate levels should be carefully controlled, as it will lead to algae growth. Algae consume oxygen, lowering the oxygen level in the tank. Using reverse osmosis decreases the overall ionic concentration of tap water and ensures suitable ionic concentrations. 

• Heavy metals
  Heavy metals (copper, iron, zinc, lead …) can be toxic to fish, and should be as low as possible. 

• Variations in pH
  Fish are very sensitive to variations in pH. A pH above 8 may prevent the growth of denitrifying bacteria, leading to the accumulation of toxic nitrogen compounds in the water. Low pH (below 6) may have toxic effects on fish. By reducing the levels of ions and organic acids present in water as much as possible, one can keep the pH of water in the vicinity of 7. 

• Hardness
  Depending on the fish species, different levels of water hardness may be required. Water hadness is important to fish health because it affects osmoregulation. Hardness must be controlled because it also has an effect on pH and pH stability. Anti-scaling agents are usually present up-stream of the reverse-osmosis membrane of water purification systems, thereby ensuring low levels of hardness. 

• Organics
  Some organics, such as pesticides, endocrine disrupters, etc. which may be present in tap water, may affect the health of the fish. Organics can also be used as nutrients by bacteria. In turn, the proliferation of bacteria will lower the oxygen level in the tank Organics can also affect spawning. Most organic molecules are efficiently removed by activated carbon and reverse osmosis. 

• Bacteria
  While some bacteria are beneficial to fish tanks because they eliminate nitrogen waste, bacterial levels in the make-up water should be kept at a low level. Bacteria can consume large amounts of oxygen, thereby depleting oxygen levels in the tank. In addition, some bacteria may affect the health of the fish. 

More Information

• Water Parameters and Your Aquarium: http://www.algone.com/water_parameters.php 
• Using Untreated Tap Water in Aquariums - Potential Problems That Can Arise & Why: http://saltaquarium.about.com/cs/dirosetup/a/aa011003.htm 
• Cichlid forum: http://www.cichlid-forum.com/articles/hardness.php

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