Why It's Different Reef Advantage Magnesium contains no ammonia. This is a common contaminant in every liquid magnesium supplement on the market. 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. So, while it will go back into solution, there will be a significant portion of time in which magnesium levels are depleted.