Salifert Magnesium fl 500ml. LIQUID. Magnesium is present in NSW (Natural Sea Water) in a fairly high concentration (1350 - 1500 mg - L). Magnesium is an essential part of chlorophyll, which is necessary for photosynthesis. Without photosynthesis algae and hence the corals, which we have in our aquariums, would not survive. Magnesium also has another important function in that it allows maintaining the correct combination of calcium concentration and alkalinity or carbonate hardness possible. Maintaining a correct magnesium concentration is therefore very important and is indirectly responsible for fast coral and calcareous algae growth. Magnesium is depleted by algae growth and also by the use of excessive kalkwasser or by going far beyond natural calcium, alkalinity and pH values. This supplement is highly concentrated. Each liter contains approximately 25000 mg of magnesium. To avoid an ionic imbalance, we properly balance the magnesium with ions such as sulfate, chloride, bromide, sodium and calcium. All ingredients are a pharmaceutical quality or even better. This ensures that no unwanted elements are added to your valuable aquarium.