How to Fix Pool Stabilizer Level: Complete CYA Guide

Tools & Supplies Needed

Find on Amazon: Taylor K-2006 Pool Test Kit , Pool Mate Cyanuric Acid , AquaChek CYA Test Strips

Quick Solution

Low Stabilizer (under 30ppm): Add cyanuric acid granules at 1 pound per 10,000 gallons to raise levels by 10ppm. High Stabilizer (over 80ppm): Drain 1/3 to 1/2 of your pool water and refill with fresh water - there's no chemical way to lower CYA levels.

Understanding Your Stabilizer Problem

Pool stabilizer, also called cyanuric acid (CYA), protects your chlorine from being destroyed by UV rays. The ideal range is 30-50ppm for traditional chlorine pools and 70-80ppm for salt water generators. Problems arise when levels drift outside these ranges, making your chlorine either ineffective or requiring dangerously high amounts.

Fixing Low Stabilizer Levels

Calculate Your Dose

Use this formula: 1 pound of cyanuric acid per 10,000 gallons raises CYA by approximately 10ppm. For example, if your 20,000-gallon pool tests at 20ppm and you want 40ppm, you need: (40-20) × 2 = 4 pounds of cyanuric acid.

Application Method

1. Test current CYA levels using a Taylor K-2006 test kit or FAS-DPD kit for accuracy
2. Calculate exact dosage needed based on your pool volume
3. Add cyanuric acid granules to your pool skimmer while the pump is running - never broadcast directly into the pool
4. Run your filtration system continuously for 24-48 hours to fully dissolve the granules
5. Retest CYA levels after 48 hours - cyanuric acid dissolves very slowly
6. Adjust your free chlorine target based on new CYA levels using the FC/CYA chart

Important: Cyanuric acid is very slow to dissolve and can take up to a week to fully register on tests. Be patient and avoid adding more until you're certain of the current level.

Fixing High Stabilizer Levels

Unfortunately, there's no chemical way to lower cyanuric acid levels. Your only options are dilution through water replacement.

Partial Drain Method

1. Test and record current CYA levels
2. Calculate how much water to drain using this formula: (Current CYA - Target CYA) ÷ Current CYA = Percentage to drain
3. For example: (100ppm - 50ppm) ÷ 100ppm = 50% water replacement needed
4. Drain the calculated percentage of water from your pool
5. Refill with fresh water
6. Run circulation system for 24 hours to mix thoroughly
7. Retest all chemical parameters and rebalance

When to Consider Full Drain

If your CYA exceeds 100ppm, a complete drain and refill may be more practical than multiple partial drains. This is especially true if you have other water balance issues like high total dissolved solids (TDS).

Adjusting Chlorine After Stabilizer Changes

Once you've corrected your stabilizer levels, you must adjust your free chlorine targets accordingly. Use these minimum FC levels based on CYA:

• CYA 30ppm: FC minimum 2ppm
• CYA 40ppm: FC minimum 3ppm
• CYA 50ppm: FC minimum 4ppm
• CYA 60ppm: FC minimum 5ppm
• CYA 70ppm: FC minimum 6ppm
• CYA 80ppm: FC minimum 7ppm

Prevention and Maintenance

Test CYA levels monthly during swimming season and after adding any stabilized chlorine products. Trichlor tablets and dichlor shock both contain cyanuric acid and will gradually raise your levels. Consider switching to liquid chlorine (sodium hypochlorite) for regular sanitizing to avoid CYA buildup.

Common Mistakes to Avoid

• Never add cyanuric acid directly to pool water - always through the skimmer
• Don't retest CYA for at least 48 hours after adding - it needs time to dissolve completely
• Avoid using stabilized chlorine products when CYA is already above 50ppm
• Don't ignore high CYA thinking more chlorine will solve algae problems - it won't work effectively

Safety Warning: When handling cyanuric acid, wear protective equipment including gloves and eye protection. The granules can be irritating to skin and eyes.