HTH™ Pool Care Chlorine Stabilizer

Pool Chlorine Stabilizer

  •
  • 4 lb.
  • Child on a red and white inner tube in a pool with HTH Pool Care branding.

HTH™ Pool Care Chlorine Stabilizer

Pool Chlorine Stabilizer

HTH™ Pool Chlorine Stabilizer is a 100% cyanuric acid pool stabilizer that protects chlorine from being destroyed by UV rays.

  • Prevents up to 90% chlorine loss from sunlight
  • Target CYA: 30-50 ppm for trichlor/dichlor pools, 60-80 ppm for saltwater pools
  • Add through the skimmer with the pump running
  • Run pump 24-48 hours before retesting (CYA dissolves slowly)
  • Compatible with all pool types, including saltwater

Product Benefits

Stops the #1 Cause of Fast Chlorine Loss

Without a chlorine stabilizer for pools, UV rays can destroy up to 90% of free chlorine within two hours. If your outdoor pool loses chlorine faster than you can add it, low CYA is almost always the cause. Test stabilizer levels using the HTH™ Test to swim™ app first before assuming you have a chlorine demand or algae problem.

Hits the Right CYA Range for Your Pool Type

Outdoor pools using trichlor or dichlor tablets need cyanuric acid pool stabilizer at 30-50 ppm. Salt chlorine generator pools typically need 60-80 ppm because the lower chlorine output benefits from more UV protection. Levels above 100 ppm can reduce chlorine effectiveness, and the only fix is partially draining the pool to dilute.

Cuts Chlorine Costs Over the Season

Properly stabilized pools use significantly less chlorine because the sanitizer stays active instead of burning off in sunlight. Many outdoor pool owners find their chemical costs drop noticeably after correcting low CYA.

Easy Skimmer Application

Add the calculated dose slowly through the skimmer with the pump running. CYA dissolves slowly, so wait 24-48 hours of pump circulation before retesting. Cyanuric acid is mildly acidic, so retest pH and alkalinity after adding stabilizer in large doses.

How to Use

How to Use

Why You Should Use This Product: This product helps to protect and extend the life of chlorine in swimming pool water. It slows the loss of chlorine caused by sunlight and helps make it easier to maintain proper chlorine levels.

For crystal clear pool water, follow the HTH 4‑Step Pool Care Program: Step 1: Test, Step 2: Balance, Step 3: Shock, and Step 4: Add Algicide regularly.

Before Adding This Product: Clean and backwash the filter. Adjust free available chlorine to 1–4 parts per million using an HTH Chlorine product. Measure the stabilizer concentration with an HTH test kit or test strips. The ideal stabilizer range is 20–25 parts per million. If stabilizer levels are above 90 ppm, replace water.

How to Add This Product to Your Pool

  1. Turn on the circulation pump.
  2. Add the correct dose of this product slowly to the skimmer.
  3. Leave the circulation pump running and do not backwash for 48 hours.
  4. Wait 48 hours before retesting.

How to Maintain the Correct Stabilizer Concentration

  1. Check stabilizer level at least twice during each swimming season.
  2. Add this product as needed.

Dosage to Raise Stabilizer

Pool Size (Gallons) 10 ppm 20 ppm 30 ppm 40 ppm
1,000 1.6 oz 3.2 oz 4.8 oz 6.4 oz
2,500 4 oz 8 oz 12 oz 1 lb
5,000 8 oz 1 lb 1.5 lb 2 lb
10,000 1 lb 2 lb 3 lb 4 lb
15,000 1.5 lb 3 lb 4.5 lb 6 lb
20,000 2 lb 4 lb 6 lb 8 lb

Ingredients

Ingredients

Principal Functioning Agent:

Cyanuric Acid: 98.5%

Constituents Ineffective as Adjuvants: 1.5%

Total: 100.0%

Safety, Storage, and Disposal

Safety

Caution: Causes eye irritation. Avoid contact with eyes, skin, and clothing. Avoid breathing dust.

Wash hands thoroughly with soap and water after handling. Do not mix this product with any other chemicals.

First Aid

If in Eyes: Hold eye open and rinse slowly and gently with water for 15–20 minutes. Call a poison control center or doctor for treatment advice.

If on Skin or Clothing: Take off contaminated clothing. Rinse skin immediately with plenty of water for 15–20 minutes. Call a poison control center or doctor for treatment advice.

If Swallowed: Call a poison control center or doctor immediately. Have person sip a glass of water if able to swallow. Do not induce vomiting unless instructed. Do not give anything by mouth to an unconscious person.

If Inhaled: Move person to fresh air. If person is not breathing, call 911 or an ambulance, then give artificial respiration if possible. Call a poison control center or doctor for further treatment advice.

In case of emergency, call 1‑800‑654‑6911. Have the product container or label available.

Storage and Disposal

Keep product in a tightly closed container when not in use. Store in a cool, dry location away from heat or open flame.

Use entire contents, then triple rinse and offer for recycling, or dispose in accordance with state and local regulations.

Do not reuse empty container.

Emergency Handling

In case of contamination or decomposition, do not reseal container. Isolate container if possible. Flood decomposing product with large amounts of water to dissolve. Dispose of container and remaining material according to local regulations.

Frequently Asked Questions

  • What is Chlorine Stabilizer and why do I need it?

    HTH™ Chlorine Stabilizer contains cyanuric acid (CYA), which acts like sunscreen for chlorine. Without it, UV rays from sunlight can destroy up to 90% of your pool's free chlorine within two hours, making it nearly impossible to maintain safe sanitizer levels.

  • What is the ideal cyanuric acid (CYA) level for a pool?

    For outdoor pools using trichlor or dichlor tablets, maintain CYA between 30–50 ppm. Salt chlorine generator pools typically need 60–80 ppm. Levels above 100 ppm can reduce chlorine effectiveness and are lowered by partially draining the pool.

  • Why is my pool losing chlorine so fast?

    Rapid chlorine loss in outdoor pools is almost always caused by low stabilizer (CYA) levels. Without enough CYA, direct sunlight destroys chlorine within hours. Test stabilizer levels and add HTH™ Chlorine Stabilizer if CYA is below 30 ppm.

  • How do I add chlorine stabilizer to my pool?

    Always check the back of HTH™ Pool Care Chlorine Stabilizer to determine the right dosage for your pool and use hthpools.com/pages/pool-calculator. Add the calculated dose directly through the skimmer with the pump running. CYA dissolves slowly — run the pump for 24–48 hours before retesting levels.

  • Does chlorine stabilizer raise or lower pH?

    Cyanuric acid is mildly acidic and may slightly lower pH and alkalinity when added in large doses. Always retest pH and alkalinity after adding stabilizer and make any necessary adjustments.

  • What happens if CYA is too high in my pool?

    High CYA (above 100 ppm) reduces the effectiveness of chlorine — a condition sometimes called 'chlorine lock' — meaning the pool requires much more chlorine to stay sanitary. The only reliable way to lower CYA is to partially drain and refill the pool.

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Quick Pool Tips

  • Always read product label directions prior to using and use only as directed

  • Always add chemicals to pool water, never the other way around

  • Never add chemicals to pool water when people are in the pool

  • Warning symbol with a triangle and exclamation mark on a blue background

    Never mix products together

  • Always store pool products in a cool, dry location and out of direct sunlight