Calcium is a major constituent of calcareous algae, skeletal material of hard corals and the skeletal needles of soft/leather corals. Calcium also fulfills many biological functions.
Quite often a too low calcium concentration retards coral and calcareous algae growth.
NSW contains 400 — 450 mg/L calcium. Which is also the value we should strive for. For a stable aquarium environment the fluctuation in calcium content should preferably not more than approx. 15 mg/L. This automatically means that the calcium test should be able to monitor comparable fluctuations.
In a healthy aquarium growth and multiplication of corals, desired calcareous algae and other organisms results in calcium depletion. Because of the importance of calcium timely corrective measures would have to be taken. For that purpose a proper calcium additive together with an accurate test kit are required.
Salifert calcium test is capable in resolving the calcium content in 10 mg/L steps. The color change is sharp and facilitates the detection of small but highly significant fluctuations in the calcium concentration. Salifert is the only one in offering a true accuracy and precision as claimed.
The kit can perform approx. 50 - 100 measurements.
Magnesium is present in NSW in a fairly high concentration (1300 - 1400 mg/L). Magnesium is an essential part of chlorophyll, which is necessary for photosynthesis. Without photosynthesis plants, including algae and the corals, which we usually have in our aquariums, would not be able to live.
Magnesium has another important function since in fact makes maintaining the correct combination of calcium concentration and alkalinity or carbonate hardness possible.
The explanation is as follows. Calcium forms with carbonates and bicarbonates an insoluble compound called calcium carbonate. Yes this is indeed an important building stone for corals and calcareous algae but then it should be formed by biological processes and be deposited at the right place. Therefore formation of calcium carbonate by chemical processes should be avoided.
Even without biological interference calcium carbonate would be formed and would deplete calcium and alkalinity or carbonate hardness without fulfilling any function. In fact it will scavenge many important trace elements as well lowering the trace element concentration.
Magnesium slows down this negative process. The lower the magnesium concentration the faster this negative process will take place and also at a much lower calcium and alkalinity/carbonate hardness value.
Maintaining a correct magnesium concentration is therefore very important and is indirectly responsible for fast coral and calcareous algae growth by virtue of making the maintenance of correct calcium and alkalinity figures possible.
Magnesium is depleted by algae and is also depleted by the use of excessive kalkwasser and by going far beyond natural calcium and alkalinity and pH values.
There are also certain brands of salt, which have or had a dramatically low magnesium content. Use of such a salt will result in permanent problems with calcium and carbonate hardness values.
The measurement of magnesium and taking corrective measures are justified. Magnesium additives should be such that no ionic imbalance is created. Furthermore many magnesium salts contain sufficient amounts of ammonia to upset biological balances. Very high-grade magnesium salts are therefore required.
Magnesium is an element which was neglected for a long time. The magnesium content of some aquariums appears to be rather low when tested. Corrective measures have to taken for a balanced reef system.
The Salifert magnesium test is very straightforward and does not suffer from calcium and strontium interferences when within certain bounds. It measures in sufficient accurate steps of 30 mg/L with a sharp color change. The kit can perform approx. 50 measurements.
Alkalinity testing and addition
Calcium alone cannot form the skeletal material of corals and allow calcareous algae to grow. Some other substances are needed as well. A few other constituents are carbonate and bicarbonate. These two substances also have a major impact on the stabilization of the pH in the proper range of 8.1 — 8.4. Such stabilization is also called buffering. The total carbonate and bicarbonate concentration is also called carbonate alkalinity or carbonate hardness. The only difference between alkalinity and carbonate hardness is a conversion factor. NSW has an alkalinity of approx. 2.7 meq/L or approx. 7.5 dKH when expressed as carbonate hardness. For a stable system the alkalinity or carbonate hardness should have a value similar to NSW or slightly higher and should preferably not fluctuate by more than 5%. This means a maximum fluctuation of 0.14 meq/L or 0.4 dKH. Therefore an alkalinity test kit should be capable in measuring in steps smaller than 0.14 meq/L.
Since the major buffer components used for coral and calcareous algae growth are bicarbonate and carbonate, they should be added to correct any decrease in alkalinity or carbonate hardness. A proper formulated buffer should function in such a way that the corrective measures results in a long lasting effect and should not upset the pH of the system. The alkalinity or carbonate hardness should be kept as stable as possible requiring highly sensitive and accurate means for testing.
The Salifert KH/Alk test is very straightforward. It measures in sufficient small steps of 0.1 meq/L or 0.3 dKH with a sharp color change. This makes detection of important yet small change possible.
The kit can perform approx. 100 - 200 measurements.