Shock Treatment
Adding a large dose of chlorine or non-chlorine oxidizer to destroy combined chlorine, algae, and contaminants.
Definition
Shock treatment (superchlorination) involves raising free chlorine to a high level — typically 10 ppm for maintenance, 10× the combined chlorine level for breakpoint chlorination, or 30 ppm for algae recovery — to eliminate combined chlorine, algae, bacteria, and other contaminants. Use calcium hypochlorite (65%) or liquid chlorine (sodium hypochlorite) for chlorine shocking. Non-chlorine shock (potassium monopersulfate) oxidizes contaminants without adding chlorine — useful when swimming must resume quickly. Always shock after dark to prevent UV degradation of the added chlorine.
Quick Facts
- Ideal Range
- N/A (raises FC to 10–30 ppm temporarily)
- Units
- ppm FC
- Also Known As
- shock, pool shock, superchlorination, hyperchlorination
The sources below support the 30 ppm green-algae-recovery figure and the 10x-combined-chlorine breakpoint-rule figure specifically. The routine-maintenance (10 ppm) figure above remains common industry guidance without a confirmed primary source and stays under review -- see the Phase 7R research log for why this specific gap remains genuinely unresolved.
Sources
- Have Algae? Confused about How Much Liquid Shock to Use? — Pool & Spa News (trade publication); content from Taylor Technologies (Professional trade publication)
- How To Shock The Pool (Chlorinate To Breakpoint) — Indiana Department of Health, Environmental Public Health Division (Government / public health authority)
Relationships
Outgoing Relationships
- solves → Algae
- solves → Green Water
- solves → Strong Chlorine Smell
- solves → Cloudy Water
- uses → Calcium Hypochlorite
- uses → Liquid Chlorine
- calculated by → formula-03
- related to → Breakpoint Chlorination