Dono, I know we disagree on the use of Dolomite, and your disliking magnesium. Mg is an essential mineral for fish. It is virtually impossible to "overdose" or have too much from using Dolomite limestone. I don't know of a single situation of magnesium being too high in a pond, nor do I know of any scientific dangers from the mineral. In fact, I only know of benefits from magnesium, but regardless, I completely disagree that "too much" dolomite sourced Ag Lime can be added to a pond. Also, I know Mg is an essential mineral, but never heard it called a heavy metal before.
I also know toxicity with any essential mineral IS possible, yet it is almost exclusively due to an imbalance in the ratios of essential minerals, and those imbalances are most often the result of an injury or disease, not merely from being present in the pond/lake water. Only so much Calcium, or magnesium will dissolve into water, and dolomite provides a source to restore both both of the essential minerals of calcium and magnesium as fish consume them from the water.
