Magnesium plays a vital role in reef aquaria: it helps maintain calcium and carbonate (composing the majority of measurable alkalinity) concentrations by limiting unwanted inorganic precipitation with each other. In the absence of adequate magnesium ions, calcium and carbonate ions bond rapidly, depleting their concentrations in the system and creating the false impression that heavier supplementation is required to re-establish the desired concentrations. No matter how much calcium is added, its natural seawater concentration of 412 ppm will never be sustained until the magnesium concentration begins to approach 1,290 ppm. Once the balance between calcium and magnesium has been established, subsequent calcium supplementation yields immediate positive results. Keeping magnesium within a range of 1,290-1,320 ppm will maintain the desired balance, and provides enough of the element to reef-building organisms for the formation of aragonite (~0.10% Mg by weight).
Instructions and Guidelines
Basic: Dissolve 2.5 grams (~½ teaspoon) of product per 20 US-gallons of aquarium water in 8-fl. oz. of fresh water; add every other day or as needed to maintain the magnesium concentration within a range of 1,290 - 1,320 ppm. When used in this fashion, 1,200 g treats up to 9,600 US-gallons (36,340 L).
Advanced: Create a stock solution by dissolving 20 grams (~4 teaspoons) of Magnesion-P in 8-fl. oz. of fresh water (preferably purified); each ml of the solution will increase magnesium concentration (”[Mg2+]”) in 1 US-gallon (3.785 L) of water by 6.0 ppm. [Reference: Each g of Magnesion-P will increase the [Mg2+] in 1 US-gallon (3.785 L) of water by 114.4 ppm.] If initial [Mg2+] in the aquarium is below 1,288 ppm, add stock sol’n at maximum rate of 10 ml per 20 US-gallons daily until desired [Mg2+] is attained, then dose daily or weekly as needed (see below). Maintain [Mg2+] within a range of +/-10 ppm. Once desired [Mg2+] has been acquired, measure aquarium's [Mg2+] at the same time each day over a one- to two-week period to determine the daily rate of magnesium uptake (i.e. the decrease in magnesium). To determine daily dosing rate (preferable to weekly dosing): estimate volume of water in entire aquarium system (US-gal.); divide the daily decrease in [Mg2+] by 6.0; multiply this number by volume of water in system to obtain daily ml of stock sol’n required to maintain stable [Mg2+].
Caution: Keep out of reach of children. Not for human consumption.
Magnesium sulfate (anhydrous), Magnesium chloride (anhydrous)