How to Fix Cloudy Pool Water: Complete Step-by-Step Guide

Tools & Supplies Needed

Find on Amazon: Taylor K-2006C Test Kit , Liquid Chlorine (Pool Bleach) , Muriatic Acid

Quick Answer

Cloudy pool water is typically caused by poor filtration, unbalanced chemistry, or insufficient sanitizer levels. The solution involves testing your water chemistry, balancing pH and alkalinity, shocking with liquid chlorine to 10-12 ppm, and running your filter continuously until the water clears completely.

Step-by-Step Guide to Clear Cloudy Water

1. Test Your Water Chemistry Completely
   Use a reliable test kit like the Taylor K-2006C to measure all parameters: Free Chlorine (FC), pH, Total Alkalinity (TA), Calcium Hardness (CH), and Cyanuric Acid (CYA). Don't rely on test strips for accurate readings. Record all numbers before proceeding - this baseline is crucial for determining the correct treatment approach.
2. Balance pH and Total Alkalinity First
   If pH is above 7.8, add muriatic acid to bring it down to 7.4-7.6. High pH reduces chlorine effectiveness and contributes to cloudiness. For every 0.2 pH reduction needed, add approximately 1 quart of muriatic acid per 10,000 gallons. If TA is above 120 ppm, lower it using muriatic acid as well. Target 80-100 ppm for regular pools, 60-80 ppm for salt water generators.
3. Determine Your Shock Level
   Based on your CYA reading, calculate the proper shock level using the FC/CYA relationship. For CYA of 30-50 ppm, shock to 12-20 ppm FC. For higher CYA levels, you'll need proportionally more chlorine. This is critical - under-shocking won't clear the cloudiness effectively.
4. Add Liquid Chlorine (Not Granular Shock)
   Use liquid chlorine (sodium hypochlorite) rather than calcium hypochlorite shock, which can contribute to cloudiness. Add approximately 1 gallon of 12.5% liquid chlorine per 10,000 gallons to raise FC by 10 ppm. Pour slowly around the pool perimeter with the pump running. Never add all chemicals at once.
5. Run Your Filter System Continuously
   Set your pump to run 24/7 until the water clears completely. This is not the time to worry about electricity costs. Clean or backwash your filter before starting, and be prepared to clean it multiple times during the clearing process as it captures the particles causing cloudiness.
6. Test FC Levels Every 8-12 Hours
   Maintain your shock level by testing and adding more liquid chlorine as needed. FC will drop as it works to clear the water. Don't let it fall below your target shock level, or the process will stall. This maintenance phase is crucial for success.
7. Brush Pool Surfaces Daily
   Brush walls, steps, and floor twice daily to help circulation and prevent particles from settling. Pay special attention to areas with poor circulation like steps, corners, and behind ladders. This mechanical action helps the chemical treatment work more effectively.
8. Continue Until Crystal Clear
   Don't stop treatment when water looks "better" - continue until it's completely crystal clear. This usually takes 3-7 days depending on how cloudy the water was initially. Only when FC holds steady overnight without dropping significantly is the process complete.
9. Resume Normal Maintenance
   Once clear, reduce FC to normal operating levels based on your CYA reading (typically 3-5 ppm for CYA of 30-50 ppm). Resume regular testing schedule and normal pump runtime. Consider what caused the cloudiness to prevent recurrence.

Common Causes of Cloudy Water

• Poor Filtration: Inadequate pump runtime, dirty filters, or undersized filtration systems can't keep up with bather load and environmental debris
• Low Sanitizer Levels: Insufficient free chlorine allows organic contaminants to build up, creating cloudiness
• Unbalanced Chemistry: High pH reduces chlorine effectiveness, while high alkalinity can cause calcium precipitation
• Heavy Bather Load: Oils, lotions, and organic matter from swimmers overwhelm sanitizer levels
• Environmental Factors: Pollen, dust, rain, and organic debris consume chlorine and add particles
• Equipment Issues: Broken or poorly functioning pumps, filters, or circulation systems

Safety Warnings and Important Notes

Warning: Always add chemicals separately and never mix them directly. Wait at least 30 minutes between different chemical additions. Wear safety equipment including goggles and gloves when handling pool chemicals, especially muriatic acid.

Avoid using clarifiers or flocculants as a shortcut - they often make problems worse by clogging filters. The SLAM (Shock Level And Maintain) method is the most reliable approach for clearing cloudy water permanently.

When to Call a Professional

Contact a pool professional if cloudiness persists after following these steps for more than a week, if you're uncomfortable handling chemicals, or if you suspect equipment failure. Recurring cloudiness often indicates underlying equipment or plumbing issues that require professional diagnosis.