If there is lack of magnesium in sea water aquaria - the concentration is obviously below 1350 mg/l (ppm) - the missing magnesium should be refilled. Otherwise coralline algae and gorgonia will not grow. Another important reason is the property of magnesium to inhibit calcium precipitation. If calcium deficiency occurs animals that need calcium are not growing. During precipitation the carbonate hardness (alkalinity) can fall down, too. You can add magnesium to the aquarium in different ways. Apart from fluid products (Magnesium-plus) granules (Turbo Magnesium) can be used as a magnesium source. It is possible to fill the material directly into the reactor. Disadvantage of this method is that you must take it out of the reactor if the magnesium concentration is reached but the calcium granules must still remain in the reactor.. A simple method is to connect the Magnesium Tube after the chalk reactor. If the magnesium concentration goes up to the optimum you can disconnect the Magnesium Tube and store it for a later application. The AquaCare Magnesium Tube is offered in two versions: the first can be fixed onto a wall and is provided with the AquaCare push-fit fittings. The second version is made for a filter sump. Specifications: * Diameter: 4.4" * Length: 28"