Which factor is NOT listed as a consideration when using copper algicides?

• A. Water hardness
• B. Target species
• C. Water flow
• D. pH

Answer: (D)

Copper algicides work best when you consider how water chemistry and the aquatic community will interact with the product. Water hardness affects copper availability: in harder water, copper can bind with minerals and form precipitates, making less copper available to target algae and potentially requiring adjustments that also raise the risk to non-target organisms. The choice of target species matters because copper can be toxic to many aquatic organisms, so you want to avoid harming desirable wildlife while achieving algae control. Water flow influences distribution and exposure time: in moving water, the treatment will disperse and dilute more quickly, which can reduce contact with algae in a given area or require different dosing to maintain effectiveness. Among the factors listed, pH is not noted as a consideration in this context, even though pH can affect copper chemistry in general; this item focuses on hardness, target species, and flow as the factors to weigh.