Free Chlorine

What It Means: Free Chlorine is the portion of chlorine in your pool or spa water that is still available to actively sanitize. Unlike Total Chlorine, which includes both active and spent chlorine, Free Chlorine represents the chemical that's still working to kill bacteria, destroy contaminants, and prevent algae.

Ideal Range: 1–4 ppm

If Free Chlorine Is Too Low: Your pool or spa may be unsafe to swim in if Free Chlorine drops below 1 ppm. Bacteria can multiply quickly, leading to cloudy water and potential health risks. To raise Free Chlorine quickly, use Super Shock Cal-Hypo, a fast-acting granular chlorine, or Liquid Chlorine from Chlor-Dash for quick-dissolving, potent sanitization. For ongoing chlorination, use 3" Chlorine Tablets in a floater or dispenser.

If Free Chlorine Is Too High: While slightly elevated Free Chlorine isn’t dangerous, high levels can lead to skin and eye irritation. Avoid swimming and allow chlorine levels to drop naturally by removing chlorine sources and running your pump. If you need a faster correction, partially drain and refill with fresh water.

Free vs. Total Chlorine: A high Total Chlorine but low Free Chlorine level means you likely have chloramines—used-up chlorine compounds that cause odor and irritation. Use Super Shock Cal-Hypo or Liquid Chlorine to break up chloramines and restore your sanitizer’s effectiveness.

Best Practices:

• Always measure Free Chlorine and compare to Total Chlorine.

• Test daily during peak season.

• Use EZ-Pour Stabilizer to help your chlorine last longer in sunlight.

Chlor-Dash Recommends:

• Super Shock Cal-Hypo (for quick sanitation and chloramine removal)

• Liquid Chlorine Refills (potent, fast-acting option for regular use or shock treatment)

• 3" Chlorine Tablets (for long-term chlorination)

• EZ-Pour Stabilizer (to protect chlorine from UV degradation)