applied to water, it forms aluminum hydroxide, the major ingredient in
Maalox. Alum precipitates
phosphorus out of the water column making it unavailable as a
nutrient for algae growth.
In addition, when applied in high concentrations, alum can
clarify the water column by concentrating and subsequently settling
alum is not an algaecide and does not directly inhibit algal growth.
Alum dosing for the purpose of stripping the water column or creating
a sediment “blanket” involves the introduction of large quantities
of alum, or an alum surrogate, over a short period of time.