Which factor is NOT indicated as affecting copper sulfate efficiency?

Which factor is NOT indicated as affecting copper sulfate efficiency?

• A. Dissolved oxygen
• B. Alkalinity
• C. Temperature
• D. pH

Answer: (A)

Copper sulfate needs copper ions to stay dissolved in the water so they can act on algae. The chemistry of the water—pH, alkalinity, and temperature—directly influences how much copper stays in that dissolved, active form. Dissolved oxygen, in contrast, doesn’t change the amount of copper that remains soluble or its toxicity toward algae in typical dosing scenarios, so it isn’t considered to affect the efficiency. Alkalinity matters because it buffers pH; when alkalinity is low, dosing can cause pH shifts that push copper out of solution as insoluble precipitates, reducing effectiveness. The pH itself is crucial because copper solubility and speciation depend on it; too high a pH promotes copper hydroxide formation and precipitation, while too low a pH can alter copper availability and algal response. Temperature influences reaction rates and algal metabolism, so warmer water can change how quickly copper works and how much is needed.

Copper sulfate needs copper ions to stay dissolved in the water so they can act on algae. The chemistry of the water—pH, alkalinity, and temperature—directly influences how much copper stays in that dissolved, active form. Dissolved oxygen, in contrast, doesn’t change the amount of copper that remains soluble or its toxicity toward algae in typical dosing scenarios, so it isn’t considered to affect the efficiency. Alkalinity matters because it buffers pH; when alkalinity is low, dosing can cause pH shifts that push copper out of solution as insoluble precipitates, reducing effectiveness. The pH itself is crucial because copper solubility and speciation depend on it; too high a pH promotes copper hydroxide formation and precipitation, while too low a pH can alter copper availability and algal response. Temperature influences reaction rates and algal metabolism, so warmer water can change how quickly copper works and how much is needed.