Here are some parameters for you.
Ammonia (NH3-4)
Natural Seawater Value: 0.010 mg/L
Acceptable Range: 0.000 to 0.050 mg/L
Ammonia levels can rise after the addition of new animals, after a water change, or after the changing of food diet. 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
Residual levels of nitrite are common in marine aquariums. 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.
Silica (Sio2-3)
Natural Seawater Value: 0.040 mg/L
Acceptable Range: 0.000 to 0.500 mg/L
Silicate is required by many types of sponges for growth/reproduction, but will also encourage brown diatom algae growth. Any level above 0.3 mg/L may cause a diatom bloom in the aquarium.
Potassium (K)
Natural Seawater Value: 390 mg/L
Acceptable Range: 350 to 450 mg/L
Potassium is rapidly depleted from aquarium water by several plant and animal metabolic processes. Maintenance of appropriate levels is critical for cellular respiration, as well as being an important nutrient for coral zooxanthellae and macro algae.
Calcium (Ca)
Natural Seawater Value: 400 mg/L
Acceptable Range: 350 to 450 mg/L
Calcium is critical to healthy coral
skeletal growth, and many other biological processes. Maintenance of calcium levels that are
at or near seawater values is an important factor in having a healthy reef aquarium.
Boron (B)
Natural Seawater Value: 4.6 mg/L
Acceptable Range: 3.0 – 6.0 mg/L
Boron is an important part of the water buffering capacity, and a lack of boron can lead to dangerous fluctuations in pH and alkalinity.
Molybdenum (Mo)
Natural Seawater Value: 0.01 mg/L
Acceptable Range: 0.0 to 0.12 mg/L
Molybdenum is important to microbial activity in the aquarium filter, and may also be important to stony coral health and reproduction.
Strontium (Sr)
Natural Seawater Value: 8.1 mg/L
Acceptable Range: 5.0 to 12.0 mg/L
Strontium is important to coral growth, as they incorporate strontium ions into their skeletal mass, particularly SPS corals. It is also important to coralline algae growth.
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.
Iodine (I¯
Natural Seawater Value: 0.060 mg/L
Acceptable Range: 0.030 to 0.090 mg/L
Iodine is required by soft corals, macro algae, and for pigment development in SPS corals.
Copper (Cu++)
Natural Seawater Value: 0.030 mg/L
Acceptable Range: 0.000 to 0.030 mg/L
Copper is fatal to marine invertebrates at levels as low as 0.05 mg/L for many species.
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.
