Copper TEA is best on which types of algae, and how should it be applied?

• A. Best on filamentous and unicell; diluted enough to ensure even distribution; spray directly on filamentous mats.
• B. Best on diatoms; applied as pellets.
• C. Best on macroalgae; injected into the water column.
• D. Only effective on planktonic algae; used with copper sulfate.

Answer: (A)

Copper TEA is a contact algaecide, so its effectiveness hinges on getting the copper to the algae where they live. It works best on filamentous algae that form visible mats and on unicellular algae that cling to surfaces because you can directly bring the product into contact with the cells. Spraying diluted copper TEA onto the filamentous mats ensures the chemical coats and penetrates the filaments, reaching the cells across the mat rather than just dispersing in the water. Dilution to achieve even distribution prevents high concentrations in one spot, which helps protect fish and other aquatic life while still delivering a lethal dose to the algae. This method targets the algae where they reside and provides thorough coverage, whereas approaches like pellets or injecting into the water column don’t reliably contact the mats.