Ammonia (NH3-4)
Natural Seawater Value: 0.010 mg/L
Acceptable Range: 0.000 to 0.050 mg/L
Any ammonia level above 0.05 mg/L is a cause for concern, and the source should be found and corrected.
Nitrite (NO2)
Natural Seawater Value: 0.010 mg/L
Acceptable Range: 0.000 to 0.100 mg/L
Levels of 0.05 or less are of little concern. If the levels are higher than this, the source should be found and corrected
Nitrate (NO3)
Natural Seawater Value: 0.050 mg/L
Acceptable Range: 0.000 to 25 mg/L
Nitrate is not toxic in and of itself, but a rising level is indicative of deteriorating water conditions, and any level above 5.0 mg/L in reef aquariums is a reason for concern.
Phosphate (PO4)
Natural Seawater Value: 0.030 mg/L
Acceptable Range: 0.000 to 0.250 mg/L
The use of a phosphate absorbing resin is recommended to keep phosphate levels below 0.05 mg/L.
Calcium (Ca)
Natural Seawater Value: 400 mg/L
Acceptable Range: 350 to 450 mg/L
Calcium is a critical parameter for coral growth in reef aquariums, and chronically low levels will cause coral mortality and loss of coralline algae and other invertebrate species.
Magnesium (Mg)
Natural Seawater Value: 1280 mg/L
Acceptable Range: 1100 to 1400 mg/L
Magnesium is a very important part of the water buffering system, and is incorporated into coral skeletons. It is also critical to any photosynthetic processes.
Alkalinity (meq/L)
Natural Seawater Value: 2.5 meq/L
Acceptable Range: 2.5 to 5.0 meq/L
Maintaining an appropriate alkalinity is crucial to maintaining a healthy aquarium. A fluctuating alkalinity will lead to serious problems in maintaining an appropriate pH, as well as problems keeping calcium and magnesium levels within required ranges.
