Why is my water cloudy?
White, cloudy water can be caused by several things, but most commonly it is due to a "bacteria bloom." A "bacteria bloom" is usually associated with "new tank syndrome". Ammonia builds up in the aquarium and the nitrogen cycle begins. As the aerobic bacteria establishes itself, it floats through the water creating a cloudy appearance. A "bacteria bloom" can also be caused by sudden increases in ammonia due to overfeeding or excess organic waste and decay. Losses of large numbers of bacteria due to power outages or other circumstances can also cause blooms.
Test the aquarium water for ammonia and nitrite. If either of these compounds are present, a bacteria culture should be added. Do not do a water change unless levels are dangerously high, or fish show signs of stress. Changing water will only lengthen the time needed for the bacteria to establish itself.
If the tank is an established aquarium (livestock has not been added in the past 2 months or longer) be sure you are not over feeding. If the problem persists there may be too many fish in the aquarium for the biological filter to adequately handle. This forces the bacteria to float freely throughout the aquarium. Additional biological filtration will need to be added or some fish may need to be removed from the tank.
The Nitrogen Cycle
The nitrogen cycle is the most important and fundamental principal of controlling a closed aquatic environment. No one should begin an aquarium without fully understanding what the nitrogen cycle is and how it works. The illustration and the description explain the four steps in the nitrogen cycle.
Fish waste, excess food and other decaying organic material break down into a toxic chemical compound called ammonia. Even in low levels, ammonia will increase the breathing rate of fish by irritating gill tissues. Damage to the body tissues of both fish and invertebrates will follow, causing disease and death.
Aerobic (oxygen needing) bacteria (Nitrosomonas) convert ammonia into nitrite. Nitrite is also a toxic chemical compound, equally as harmful to fish as ammonia. Nitrite destroys the hemoglobin in the blood of fish and invertebrates. Without hemoglobin the blood cannot carry oxygen.
The nitrite is converted by a second aerobic bacteria (Nitrobacter) into a far less toxic compound called Nitrate. Nitrate levels in excess of 50 ppm in freshwater or 10 - 15 ppm in marine aquariums can cause stress, encourage disease and stunt growth. Be sure to regularly monitor nitrates with a nitrate test kit
Nitrates can be removed by several means. Small amounts are absorbed naturally by plants and algae. The remaining nitrates can be effectively eliminated with a good aquarium maintenance program. Regular water changes, cleaning filter cartridges, vacuuming substrates and removing detritus (organic waste buildups) will solve most nitrate problems. If problems persist, nitrate removing medias, denitrators and protein skimmers
may be needed. Denitrators will biologically remove nitrates while protein skimmers will remove organic waste before the Nitrogen Cycle breaks them down into nitrate. (Due to the low nitrate levels required in saltwater aquariums a protein skimmer
is recommended as a basic piece of equipment.)
Note: Some home water supplies contain nitrates. Water changes with this water will not be effective. A reverse osmosis or deionization unit may be necessary in these cases.
Starting the Nitrogen Cycle