If your free chlorine level is low while your total chlorine level is high, it typically indicates that you need to shock your spa. This involves adding an oxidizer to break down combined chloramines.
Here's a breakdown:
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The Problem: Low Free Chlorine (FC) means chlorine is bound to contaminants and is ineffective at sanitizing. High Total Chlorine (TC) means you have a lot of chlorine present, but much of it is used up and no longer active. The difference between TC and FC is combined chlorine (chloramines), which is what you're trying to eliminate.
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The Solution: Shocking the Spa Shocking is the process of adding a high dose of oxidizer to break apart those combined chloramines.
How to Shock Your Spa:
- Test Your Water: Use a reliable test kit or strips to confirm your FC, TC, pH, and alkalinity levels.
- Adjust pH and Alkalinity: Ideal pH is typically between 7.2 and 7.8. Ideal alkalinity is typically between 80 and 120 ppm. Correct these imbalances before shocking, as they can affect chlorine's effectiveness.
- Add Oxidizer: Use a non-chlorine shock (like potassium monopersulfate – often sold under brand names like Dazzle Amaze or Mineraluxe Oxygen). Follow the product instructions exactly for dosage. Over-shocking can cause problems too.
- Run Jets/Circulation: Turn on the spa jets or circulation pump to help distribute the shock throughout the water.
- Leave Cover Off: Leave the spa cover off for at least 20-30 minutes (or longer if specified by the product instructions) to allow the chloramines to off-gas.
- Retest and Wait: After the recommended time (usually several hours), retest the water. You may need to wait for the chlorine levels to return to a safe level (typically 1-3 ppm) before using the spa again.
Important Considerations:
- Follow Product Instructions: Always adhere to the specific instructions provided by the manufacturer of your chosen sanitizing or shocking product.
- Regular Testing is Key: Test your spa water regularly (at least 2-3 times per week) to maintain proper chlorine levels and prevent issues.
- Spa Volume Matters: The amount of chemicals you need will depend on the volume of water in your spa. Know your spa's capacity.
- Persistent Problems: If you consistently have trouble maintaining proper chlorine levels, consider draining and refilling your spa, checking your filter, and evaluating your sanitation system.
