Sera test magnesium Mg to the reliable and exact determination of the magnesium content in the sea water. Magnesium fulfills two key functions in marine aquariums: it keeps calcium in solution and thus in a bioavailable form, and it is an essential nutrient for calcareous red algae and soft corals, which require it to form their spicules. For a stable and healthy reef aquarium, the magnesium level should be about 1,300 mg/l (ppm). The Sera Magnesium Test reliably measures the magnesium level in 60 mg/l (ppm) steps, allowing precise adjustment in the aquarium. Sera Magnesium Test Mg+ monitor the magnesium level in aquariums according to scientific standards+ precise measurement in 60 mg/l (ppm) steps+ allows precise adjustment of the Mg level, for optimal coral growth+ complete kit with vial, syringe, measuring spoon, and evaluation chart for precise water analysis+ with a readily understandable video tutorial for easy use+ for approx. 16,000 mg magnesium