How to Lower Pool Alkalinity: Complete Step-by-Step Guide

Tools & Supplies Needed

Find on Amazon: Taylor K-2006C Test Kit , Muriatic Acid , Sodium Bisulfate

Quick Answer

High alkalinity can cause cloudy water, scaling, and difficulty balancing pH. The most effective way to lower alkalinity is by adding muriatic acid (hydrochloric acid) or sodium bisulfate (dry acid) to your pool water. These acids will reduce both alkalinity and pH simultaneously.

Step-by-Step Process to Lower Pool Alkalinity

1. Test Your Current Alkalinity Level
   Use a reliable test kit like the Taylor K-2006C to measure your total alkalinity (TA). Target alkalinity levels are 80-120 ppm for regular chlorine pools and 60-80 ppm for salt water generator pools. Record your starting TA and pH levels.
2. Calculate Chemical Dosage
   For muriatic acid: Use approximately 1 quart (32 oz) per 10,000 gallons to lower TA by 10 ppm. For sodium bisulfate: Use approximately 1.5 pounds per 10,000 gallons to lower TA by 10 ppm. Always start with smaller amounts and add more if needed.
3. Prepare Safety Equipment
   Safety Warning: Always wear safety goggles, rubber gloves, and closed-toe shoes. Work in a well-ventilated area and never mix chemicals together.
4. Turn Off Pool Equipment
   Shut off your pool pump, heater, and any automatic chemical feeders. This prevents immediate circulation and allows the acid to work more effectively in localized areas.
5. Add Acid to Deep End
   Pour the muriatic acid slowly into the deepest part of your pool, never into the skimmer or near pool equipment. If using liquid acid, pour it directly into the water in a steady stream while walking around the deep end perimeter.
6. Wait Before Circulating
   Allow the acid to sit without circulation for 1 hour. This helps the acid work on alkalinity rather than immediately affecting pH throughout the entire pool.
7. Turn Pump Back On
   After the waiting period, turn your circulation system back on and run it for at least 4-6 hours to thoroughly mix the chemicals throughout the pool.
8. Retest Water Chemistry
   Wait 6-8 hours after adding chemicals before retesting. Test both alkalinity and pH levels. The pH will likely drop significantly and need adjustment.
9. Adjust pH if Necessary
   If pH drops below 7.2, add sodium carbonate (soda ash) to raise it back to the ideal range of 7.4-7.6. Use approximately 6 oz per 10,000 gallons to raise pH by 0.2 units.
10. Repeat if Needed
    If alkalinity is still too high, repeat the process. Never add more than the equivalent of 1 quart of muriatic acid per 10,000 gallons in a single treatment.

Choosing Between Muriatic Acid and Sodium Bisulfate

Muriatic Acid (Liquid)

Muriatic acid is more cost-effective and works faster than dry acid. It's the preferred choice for most pool professionals. However, it produces fumes and requires more careful handling. The liquid form dissolves immediately and begins working right away.

Sodium Bisulfate (Dry Acid)

Sodium bisulfate is safer to handle and store, making it ideal for pool owners who prefer a granular product. It's more expensive than muriatic acid but eliminates concerns about fumes and spills. Dissolve it in a bucket of pool water before adding to prevent undissolved granules from settling on pool surfaces.

Understanding the Alkalinity-pH Relationship

When lowering alkalinity, your pH will also decrease significantly. This is normal and expected. The key principle is that alkalinity acts as a buffer for pH - high alkalinity makes pH changes difficult, while proper alkalinity allows for stable pH control.

After achieving target alkalinity levels, you'll find pH much easier to maintain within the ideal 7.4-7.6 range using smaller amounts of pH adjusters.

Common Mistakes to Avoid

• Adding too much acid at once: This can cause pH to crash below 7.0 and potentially damage pool surfaces
• Not waiting before circulation: Immediate circulation reduces the acid's effectiveness on alkalinity
• Using the skimmer method: Adding acid through skimmers can damage equipment and create dangerous fume concentration
• Ignoring safety protocols: Acid burns are serious - always use proper protective equipment
• Not retesting: Water chemistry changes take time to stabilize - test before making additional adjustments

Maintenance Tips

Once you achieve proper alkalinity levels, maintain them by testing weekly and making small adjustments as needed. High alkalinity typically results from using calcium hypochlorite shock treatments or alkaline pH increasers. Consider switching to liquid chlorine for routine sanitizing to minimize alkalinity increases.

Keep detailed records of your chemical additions and test results to better understand your pool's specific needs and seasonal patterns.