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What is TriChlor?

Quick Reference

  • Chemical Name: Trichloroisocyanuric Acid
  • Available Chlorine: 90% (highest concentration)
  • pH Range: 2.8-3.0 (acidic)
  • Cyanuric Acid: Contains 54% stabilizer
  • Best For: Daily maintenance, automatic feeders, outdoor pools
  • Shelf Life: 5+ years when stored properly

What is TriChlor?

TriChlor, short for trichloroisocyanuric acid, is a stabilized chlorine compound containing 90% available chlorine—the highest concentration of any pool sanitizer. Unlike liquid chlorine or calcium hypochlorite, TriChlor includes cyanuric acid (CYA) as part of its molecular structure, providing built-in UV protection for outdoor pools.

Available primarily in tablet or stick form, TriChlor dissolves slowly and consistently, making it ideal for automatic chlorinators and floating dispensers. Its slow-release properties provide steady sanitization over extended periods, reducing the need for daily chemical additions.

Important: TriChlor contains 54% cyanuric acid by weight. Regular use will continuously increase your pool's CYA levels, requiring careful monitoring to prevent over-stabilization.

How TriChlor Works

When TriChlor dissolves in water, it releases both hypochlorous acid (the sanitizing agent) and cyanuric acid (the stabilizer). This dual action provides immediate disinfection while building up protective CYA levels that shield chlorine from UV degradation.

The cyanuric acid forms a weak bond with chlorine molecules, creating a "reserve" of protected chlorine that's released as free chlorine is consumed. This stabilizing effect is crucial for outdoor pools but can become problematic if CYA levels exceed recommended ranges.

Advantages of TriChlor

  • Highest Chlorine Content: 90% available chlorine provides maximum sanitizing power per unit weight
  • UV Protection: Built-in cyanuric acid prevents chlorine degradation from sunlight
  • Slow Release: Steady dissolution provides consistent chlorination for days or weeks
  • Convenient Application: Perfect for automatic feeders, floaters, and skimmer baskets
  • pH Buffering: Acidic nature helps counteract pH rise from other pool chemicals
  • Long Shelf Life: Properly stored tablets remain effective for 5+ years
  • Cost Effective: High concentration and slow dissolution reduce frequency of additions

Proper Application

Pro Tip: Never place TriChlor tablets directly in the pool or skimmer basket for extended periods. The high concentration can damage pool surfaces, equipment, and create dangerous chlorine gas pockets.

Automatic Chlorinators: Use properly sized chlorinators with flow control to regulate dissolution rate. Typically 1-3 tablets per 10,000 gallons, adjusted based on bather load and weather conditions.

Floating Dispensers: Load 1-2 tablets and adjust vents to control dissolution speed. Remove during swimming and storms to prevent localized over-chlorination.

Erosion Feeders: Install offline feeders to ensure even distribution and prevent equipment damage from concentrated chlorine solution.

Shock Treatment: TriChlor is NOT recommended for shock treatments. Use calcium hypochlorite or liquid chlorine for rapid chlorine boosts.

Free Chlorine to CYA Ratio Management

TriChlor has a pH of 2.8-3.0, making it highly acidic. While this helps counteract pH rise from other chemicals, it can drive pH too low with heavy use, requiring sodium carbonate or borax additions to maintain proper balance.

Critical: Each 1-pound of TriChlor adds approximately 0.54 pounds of cyanuric acid to your pool. Monitor CYA levels monthly and maintain proper FC:CYA ratios for effective sanitization.

As cyanuric acid levels increase, higher free chlorine levels are required for effective sanitization. The relationship follows this general guideline:

  • CYA 30-50 ppm: Maintain FC at 2-4 ppm (target range for most pools)
  • CYA 60-80 ppm: Maintain FC at 4-6 ppm
  • CYA 80-100 ppm: Maintain FC at 6-8 ppm
  • CYA above 100 ppm: Consider partial water replacement to restore proper ratios

CYA Management Strategies:

  • Test CYA levels monthly during swimming season
  • Alternate between TriChlor and unstabilized chlorine products
  • Partially drain and refill pool when CYA exceeds 100 ppm
  • Consider liquid chlorine or calcium hypochlorite for shock treatments

Application Methods

Method Pros Cons Best For
Automatic Chlorinator Precise control, even distribution Equipment cost, maintenance required Primary sanitization system
Floating Dispenser Inexpensive, easy to use Uneven distribution, weather dependent Supplemental chlorination
Skimmer Basket Convenient, good circulation Can damage skimmer, concentrated solution Short-term use only

Storage and Handling

TriChlor requires careful storage due to its strong oxidizing properties:

  • Dry Environment: Store in original containers in cool, dry locations away from moisture
  • Chemical Separation: Keep away from acids, bases, and organic materials
  • Incompatible Products: Never store with calcium hypochlorite, liquid chlorine, or other oxidizers
  • Container Integrity: Ensure tight seals to prevent moisture absorption and gas escape
  • Fire Safety: Store away from heat sources and combustible materials

Safety Precautions

⚠️ EXTREME DANGER: Never mix TriChlor with calcium hypochlorite, acids, or other pool chemicals. This can cause violent explosions and release deadly chlorine gas.
  • Wear gloves and eye protection when handling tablets
  • Avoid breathing dust or vapors from tablets
  • Use dedicated tools that have never contacted other pool chemicals
  • Never crush or break tablets—use whole tablets only
  • Store away from children and pets in locked areas
  • Ensure adequate ventilation in storage areas
  • Never add TriChlor to skimmers during pump downtime

Common Issues and Solutions

Issue Cause Solution
High chlorine reading but poor sanitization Excessive cyanuric acid levels (>100 ppm) Partial drain/refill to reduce CYA levels; increase FC:CYA ratio
Low pH despite balanced chemicals TriChlor's acidic nature Add sodium carbonate; consider alternating with liquid chlorine
Rapid tablet dissolution High water flow or temperature Reduce chlorinator flow rate or use larger tablets
Equipment damage/staining Concentrated chlorine exposure Use proper feeders; never place tablets directly in pool

TriChlor vs. Other Chlorine Products

Product Available Chlorine pH Effect CYA Content Best Use
TriChlor 90% Lowers pH 54% Daily maintenance, automatic feeders
Calcium Hypochlorite 65-70% Raises pH 0% Shock treatment
Liquid Chlorine 10-12.5% Raises pH 0% Daily sanitizing, shock treatment

TriChlor offers excellent convenience and UV protection for outdoor pools, making it ideal for automated sanitization systems. However, careful monitoring of cyanuric acid levels and proper FC:CYA ratio management is essential to maintain effective sanitization while preventing over-stabilization issues.