Severely depleted levels of magnesium (below 800 mg/L) can cause depressed pH levels and an inability to maintain proper calcium levels. The most frequent causes of magnesium deficiency are use of kalkwasser, frequent overdosing of a carbonate additive, or low levels in the salt mix itself. Kalkwasser, for instance, precipitates magnesium as magnesium hydroxide while excess carbonates precipitate it as magnesium carbonate. In both cases, this means that magnesium that was present in the water is now unavailable. Of the two, magnesium hydroxide and magnesium carbonate, the former is more problematic; it is extremely insoluble. Once magnesium has precipitated as magnesium hydroxide, it will never redissolve. Magnesium carbonate will redissolve; however, it does so slowly. So, while it will go back into solution, there will be a significant portion of time in which magnesium levels are depleted.

Directions
BEGINNER: Use 5 g (1 level teaspoon) per 80 L (20 gallons*) twice a week. Dissolve in at least 250 mL (1 cup*) of freshwater. ADVANCED: Check magnesium level, then follow addition regimen above until magnesium is adjusted to 1200–1350 mg/L. Each 5 g/80 L will raise magnesium by about 5 mg/L. Amount or frequency can be adjusted, but do not exceed 25 g/80 L per day. Thereafter, use as required to maintain magnesium. EXPERT: After determining the magnesium depletion rate, set up a continuous drip system. Use the following formula to determine how much to add to your top-off water: g=vm/80 (g=grams to add to top off water, v=volume of tank in liters, m=amount to raise magnesium in mg/L). For example, if you want to raise magnesium by 10 mg/L in a 200 liter tank, then you would add (200x10)/80=25 g into the top-off water. [For reference: 1 gallon*=3.8 liters, 5 g=1 teaspoon*]. HINTS: Use the Reef Status™ Magnesium, Carbonate & Borate to check magnesium levels.

DO NOT OVERDOSE: Excess magnesium may enhance the loss of carbonate alkalinity. Do not directly mix with any carbonate supplement. Best if magnesium & carbonate additives are added on alternate days or at least 30 minutes apart. Slight clumping of this product may be encountered but does not impact its use; any clumps will break up very easily.