1. Insufficient Algicide Dosage: Concentration below effective level.
Algicide efficacy is directly related to concentration. Underdosing may only suppress, not kill, algae.
Recommendation: Precisely calculate and dose based on pool volume and product concentration.
2. Incorrect Algicide Selection (Mismatched to Algae Type):
Different algae types (green, black/mustard, yellow) vary in sensitivity. Stubborn algae (e.g., black algae) resist standard algicides.
Recommendation: Use targeted algicides (e.g., cationic polymer-based or blended types) suited to the specific algae present.
3. Algae Biofilm Formation Blocking Penetration:
Untreated algae form protective biofilms on walls, pipes, and crevices, shielding cells. Surface-acting algicides cannot penetrate.
Recommendation: Mechanically scrub surfaces, perform shock dosing with algicide, and clean the filter system.
4. Excessive Nutrients (Phosphorus/Nitrogen) in Water:
High phosphate/nitrate levels act as algae "food," enabling rapid regrowth even after initial kill.
Recommendation: Regularly use phosphate removers to control nutrient load.
5. Unsuitable pH Level for Algicide Efficacy:
Most algicides work best within pH 6.5–8.0. Deviations reduce activity.
Recommendation: Test and adjust pH before algicide application.
6. Neutralization/Reaction with Other Pool Chemicals:
Algicides can be deactivated by chlorine, potassium permanganate, etc., especially if added immediately after chlorine.
Recommendation: Follow dosing sequences, allow intervals between chemicals, and consult supplier compatibility guides.
7. Poor Filtration/Circulation:
Inadequate circulation creates "dead zones" untreated by algicide. Dirty filters harbor algae, causing reinfection.
Recommendation: Ensure efficient pump/filter operation; clean filters and returns regularly.
8. Inadequate Treatment Frequency/Maintenance:
Single treatments lack lasting control. Algae regrow rapidly in warm, sunny conditions without preventive maintenance.
Recommendation: Implement regular water testing and scheduled algicide maintenance, not just reactive treatments.
Key Takeaway: Algae Control is a System
Algicides are just one component. Effective control requires:
✔️ Correct dosing & application
✔️ Balanced water chemistry (pH, sanitizer, nutrients)
✔️ Mechanical filtration & physical cleaning
✔️ Consistent maintenance & data monitoring.