Foam Around Pond Edges After Algaecide: Overdose or Surfactant?

270-gal preformed pond. Added algaecide for murk/algae. Now white foam at edges, on floating objects. Fish not eating (temp drop). Cause?

Likely Causes

1. Algaecide Surfactants: Many liquid algaecides contain surfactants that foam when agitated (waterfall, spitters). Harmless but ugly. Dissipates in days.
2. Overdose: 270 gal is tiny. Easy to overdose. Foam = excess chemical.
3. Protein Foam: Organic buildup (rare in new pond).

Your "Filters" Are Just Pumps

300 & 330 GPH pumps ≠ filtration. You need a biofilter (media for bacteria) and mechanical filtration (sponge/mat).

Action Plan

1. Test Water: Ammonia, nitrite, pH. Adjust.
2. Water Change: 20% to dilute algaecide. Dechlorinate.
3. Add Real Filtration: Pressurized filter (like Fish Mate) or waterfall box filter with media.
4. Beneficial Bacteria: Jump-start biofilter.
5. Stop Algaecide: Fix the root cause (nutrients, light, filtration), not the symptom.

Foam will fade. Fix the filtration.