Chemistry & herbicides
Copper sulfate
Also known as: chelated copper, copper algaecide
Copper sulfate (and its chelated formulations) is the most common algaecide in US pond management. Kills filamentous algae and cyanobacteria within 24–72 hours of contact. The dead biomass then sinks, decays, releases the phosphorus it absorbed back into the water column, and fuels a new bloom in 2–4 weeks. Copper alone is a treadmill — algaecide treats the symptom; aeration, buffer plantings, and nutrient reduction treat the cause. Toxicity to fish is rate-dependent; underdosing fails, overdosing kills the fishery.
Related terms
- Filamentous algaeBright green stringy mats of single-celled algae that bloom on nutrient-loaded ponds in warm weather.
- Phosphorus loadingThe rate of phosphorus inputs to a water body; the limiting nutrient for most freshwater algae blooms.
- EutrophicationThe over-enrichment of a water body with nutrients, leading to chronic algae blooms and oxygen crashes.