How to Adjust Cyanuric Acid Levels in a Pool

Pool owners add cyanuric acid (CYA) to pools to slow down the dissipation of chlorine in the pool as the sun shines on it. Cyanuric acid is only for outdoor pools in direct sunlight and never for pools indoors or in shade all day. Owners add the acid to achieve the proper stabilization, which is between 30 and 50 parts per million (ppm). If the level of cyanuric acid in the pool is over 100 ppm, you must remove it manually.

Things You'll Need

• Cyanuric acid test strips
• Cyanuric acid
• Warm water
• Bucket
• Submergible sump pump
• Garden hose

Instructions

Adding Acid

1. Test the water with the vyanuric acid test strip. Stick the strip in the water and pull it out. Compare the color of the test strip to the color chart that comes with the kit. If the level is below 30 ppm cyanuric acid in the pool water, you need to add acid to raise the level.

2. Fill a bucket with warm water. Add the correct amount of cyanuric acid to dissolve. For a pool that has 25,000 gallons of water, dissolve 2 lbs. of acid to raise the CYA 10 ppm. Raise the CYA 20 ppm in a 25,000 gallon pool by dissolving 4 lbs. of acid and to raise the CYA in the pool 40 ppm, use 3 1/4 lbs. of acid to the warm water.

3. Allow the acid to dissolve in the warm water. Pour the dissolved CYA in the deep end of the pool, starting at one end of the deep end, walking around to the other side of the deep end while pouring in the solution.

Removing Acid

1. Rent or purchase a submergible sump pump from an equipment store or from a local pool retailer. There is no way to reduce the amount of cyanuric acid in the pool water, except for draining out some water.

2. Attach the garden hose to the sump pump. Run the hose away from the pool so that the removed water does not drain back into the pool.

3. Turn on the sump pump. Place the sump pump in the pool water 6 inches deep. Use something heavy to lie on the garden hose and hold the sump pump in position. Keep watching the pump and lower it into the water as the pool drains. You need to drain the pool half way. Use the shallow end of the pool to judge how much water is removed and not the deep end.

4. Remove the sump pump when half of the water in the pool is drained out. Disconnect the garden hose from the sump pump and place the end in the water. Attach the other end to the water faucet. Turn on the water and fill the pool up so that the water level is between the skimmer plate marks inside the pool.

5. Retest the water to assure the CYA level is low enough.

Tips & Warnings

• Seek professional help if the cyanuric acid level will not go down. You may need to completely drain the pool, something you should not attempt yourself without guidance.

References

• North Carolina State: Water Chemistry For Swimming Pools
• Lincoln, Nebraska Government: Fact Sheet on Cyanuric Acid and Stabilizer Chlorine Products
• Pool Manual: Cyanuric Acid