While not as common as some of the other foulants discussed in this section, aluminum contamination in a cooling water stream can pose a serious fouling potential. Like iron, calcium, and zinc, aluminum in the presence of orthophosphate is extremely insoluble and can form an aluminum phosphate sludge. Typically, though, the foul ant formed when aluminum is present is a combination of various other foulants such as suspended mud or silt.

A typical source of aluminum contamination is alum carryover from clarifiers. Since there is not a deposit control agent specific for preventing aluminum precipitation, it is important to ensure proper clarifier operation. However, when this is not possible, a surfactant may help reduce the severity of the deposition. If phosphate is present, a deposit control agent specific for preventing phosphate fouling may be warranted. If you encounter an aluminum fouling problem, consult CUT marketing for specific product recommendations