Algae Die-Off After Well Upgrade: Ozone & Snail Deaths

750-gal pond, 4 yrs healthy. Well upgrade → higher ozone. Algae turning brown, bubbly, stringy, clogging filter. Snails dying (thin, holed shells). Fish/frogs OK. pH 7.4+ (kit max).

Ozone & Water Chemistry

Ozone oxidizes organics, kills algae, but can create toxic byproducts (bromate if bromide present). It also oxidizes copper pipes → copper ions (toxic to snails, safe for fish at low levels).

Action Plan

1. Test well water: Copper, bromide, ozone residual, full mineral panel.
2. Remove dead algae daily—decomposing algae releases toxins.
3. Reduce/stop Algaefix—chemicals + ozone = unknown interactions.
4. Snail deaths: Likely copper toxicity or starvation (algae gone).
5. Adaptive maintenance: Adjust one variable at a time (feeding, water changes, filter cleaning).

Well water change is the smoking gun. Comprehensive testing is essential before further treatment.