Waterbody managers may try aerating iron-rich waters as a strategy to reduce phosphorus concentrations in order to limit nuisance aquatic plant and algal growth, hoping for the results described in Example 1. This effort may be thwarted, however, if sulfur is plentiful in the water. Iron has the chemical characteristic of preferring to bind with sulfur instead of phosphorus, when there is adequate oxygen present, as with an aerator. Therefore, in aerated sulfur-rich waters, phosphorus would still be available for aquatic plant and algae use, and the expected decline in aquatic plant and algal growth would not be realized.

An understanding of the role that iron plays in the phosphorus cycle is a particularly important management tool in waterbodies where the primary supply of phosphorus is that which is dissolved from the bottom sediments into the water column. In this situation, iron manipulation is one of only a few management strategies that have the potential to limit phosphorus availability effectively.

In Florida
Waterbodies in the Florida LAKEWATCH database had average total iron concentrations ranging from 0 to 2.4 mg/L. Over 75% of these waterbodies had total iron concentrations less than 0.24mg/L. The highest concentrations of iron are found in Florida's highly colored waterbodies. This is understandable because iron combines easily with organic molecules (like those that make water appear tea-colored), probably causing the water to become iron-enriched.

Health Concerns
Iron is not a known threat to human health. It may, however, be toxic to invertebrates and fish. Canada has issued a guideline stating that total iron should not exceed 0.3 mg/L, which is higher than the concentration found in most Florida lakes. If iron is a cause of toxicity to Florida's aquatic organisms, and there is no evidence that it is, only a few Florida lakes are potentially at risk.