Can I Swim in a Green Pool? Safety Risks & Solutions

Tools & Supplies Needed

Find on Amazon: Taylor K-2006 Pool Test Kit , Liquid Chlorine Pool Shock , Pool Brush for Algae Removal

Quick Answer

No, you should absolutely not swim in a green pool. Green water indicates a significant algae bloom and potentially dangerous bacterial growth that can cause serious health problems including skin infections, eye irritation, respiratory issues, and gastrointestinal illness. The green color means your sanitizer levels are insufficient to maintain safe swimming conditions.

Why Green Pools Are Dangerous

1. Harmful Bacteria Growth: When chlorine levels drop below effective ranges (typically below 1-3 ppm depending on CYA levels), harmful bacteria like E. coli, Pseudomonas, and Legionella can multiply rapidly in the warm, nutrient-rich environment.
2. Algae Toxins: Some algae species produce toxins that can cause skin rashes, eye irritation, and respiratory problems when swimmers are exposed to contaminated water.
3. Poor Water Chemistry: Green pools often have imbalanced pH levels (usually high), which reduces sanitizer effectiveness and can cause chemical burns or skin irritation.
4. Reduced Visibility: You cannot see the pool bottom, creating drowning hazards as you cannot spot swimmers in distress or identify pool obstacles.
5. Equipment Damage Risk: The same conditions causing green water can damage pool equipment, potentially creating additional safety hazards.

Health Risks of Swimming in Green Water

Swimming in algae-contaminated water exposes you to several serious health risks:

• Skin infections: Folliculitis, impetigo, and cellulitis from bacterial contamination
• Eye problems: Conjunctivitis, corneal infections, and severe irritation
• Ear infections: Swimmer's ear and inner ear infections
• Respiratory issues: Asthma exacerbation, pneumonia, and lung infections
• Gastrointestinal illness: Nausea, vomiting, diarrhea from accidentally ingesting contaminated water
• Open wound infections: Any cuts or scrapes can become severely infected

Step-by-Step Process to Make Your Pool Safe Again

1. Test Your Water Chemistry: Use a reliable test kit like the Taylor K-2006 to measure Free Chlorine (FC), Combined Chlorine (CC), pH, Total Alkalinity (TA), and Cyanuric Acid (CYA) levels. Record these baseline numbers.
2. Calculate Your Shock Level: Based on your CYA reading, determine the required shock level using the FC/CYA chart. For CYA of 30-50 ppm, you'll need to maintain FC at 12-20 ppm during the SLAM process.
3. Adjust pH if Necessary: If pH is above 7.6, lower it to 7.2-7.4 using muriatic acid. High pH reduces chlorine effectiveness, making the clearing process much slower.
4. Begin the SLAM Process: Add liquid chlorine (sodium hypochlorite) to reach your calculated shock level. Avoid cal-hypo shock products as they add calcium and CYA. You'll typically need 1-2 gallons of 12.5% liquid chlorine per 10,000 gallons initially, though the exact amount depends on your starting FC and target shock level based on CYA.
5. Run Filtration Continuously: Keep your pump and filter running 24/7 during the clearing process. Clean or backwash your filter when pressure rises 8-10 psi above your clean baseline.
6. Brush Pool Surfaces: Brush walls, steps, and floor twice daily to break up algae biofilm and circulate dead algae to the filter.
7. Test and Add Chlorine Regularly: Test FC levels every 2-4 hours during daylight and add chlorine as needed to maintain shock level. Expect to add significant amounts initially as the chlorine kills algae and bacteria.
8. Monitor Progress: The water should begin clearing within 24-48 hours. Continue the process until you can see the pool bottom clearly and maintain shock level overnight without significant chlorine loss.
9. Pass the Overnight Chlorine Loss Test (OCLT): When FC loss is less than 1 ppm overnight and CC is 0.5 ppm or less, your pool is nearly ready.
10. Return to Normal Levels: Once the OCLT passes, reduce FC to normal operating range (1-4 ppm based on CYA level) and resume regular maintenance.

Prevention Tips

To prevent future green pool situations:

• Test water 2-3 times per week using a reliable test kit
• Maintain proper FC levels based on your CYA reading
• Keep CYA between 30-50 ppm for regular chlorine pools
• Brush pool surfaces weekly to prevent algae attachment
• Ensure adequate circulation and filtration
• Address water balance issues promptly
• Test for phosphates and metals periodically - high levels can interfere with chlorine and cause recurring algae

When to Call a Professional

Consider professional help if:

• The pool has been green for more than 2 weeks
• You're uncomfortable handling large amounts of chlorine
• Equipment problems are preventing proper circulation
• Multiple SLAM attempts have failed
• You suspect the pool has structural issues contributing to the problem

Remember: The clearing process typically takes 3-7 days depending on the severity of the algae bloom and your diligence in maintaining shock levels. Do not swim until the water is crystal clear and chemistry is balanced.