Home Up Water Testing pH & Alkalinity Sanitizer Algae Control Stabilizer Mineral Control Cleaning Products Chemical Safety Pool Gallonage



Stabilizer is also known as:

bulletCyanuric Acid
bulletIsocyanuric acid

When a chlorine disinfectant is used outdoors, the free available chlorine residual is driven off by the ultraviolet rays of the sun.  Maintaining a certain level of stabilizer keeps the free available chlorine from dissipating.  The most common form of stabilizer used in pool water is cyanuric acid.

The NSPI recommended range of stabilizer in the pool water is from (minimum) 10 ppm, to 150 ppm (maximum), with the ideal range being 30-50 ppm.

Cyanuric acid is a white powder or granular product which is usually added to the pool water through the skimmer.  Backwash the pool filter first, then remove the pump basket and restart the system on "filter" and add Cyanuric acid slowly to the skimmer closest to the pump.  Stabilizer dissolves very slowly so we add it to the skimmer to allow the product to reach the pool filter where it can dissolve slowly over time.  Do not backwash the pool filter for a few days after adding stabilizer.  It needs this time to dissolve.  Cyanuric acid has a low pH.  Adjust the pH level of the pool water to 7.5 - 7.8 once the stabilizer has fully dissolved or after a couple of days.

When starting a freshly filled pool with untreated water, usually add 6 pounds of cyanuric acid per 20,000 gallons of water to yield about 30 ppm stabilizer in the water.  Test and adjust the cyanuric acid level during the pool season.  The chlorinated isocyanurates (dichlor, trichlor) are stabilized chlorine products, containing 50% or more of cyanuric acid.  With these disinfectants, each chemical addition automatically adds stabilizer.  Cyanuric acid also acts as a weak buffer and is picked up on an alkalinity test.

If the cyanuric acid level becomes too high (over 100-150 ppm), the pool water can be diluted with untreated water to reduce the level to the recommended range.

Remember that a stabilizer is used to protect chlorine from UV light of the sun, and should not be used on indoor pools or spas or with non-chlorine disinfectants.  If bromine has been used to disinfect pool water and the owner wishes to change to a stabilized chlorine disinfectant, the pool should be drained and refilled before switching.  If the switch is from stabilized chlorine to bromine, no draining is necessary.

Cyanuric acid properties:

bulletpH is 4.5
bulletSlow dissolving
bulletMaximum solubility = 1600 ppm
bulletNot destroyed by any pool chemical
bulletRemoved only by draining, splash out, and backwash
bullet1lb/5000 gallons yields 25 ppm CYA

Hit Counter

~ Expert Pool & Spa, Inc. ~
"Ask The Experts!"
Omaha Nebraska
Ask your questions on our FORUM!
Please do not call us on the telephone unless you live in Lincoln or Omaha Nebraska areas. Telephone consultation is $75 per hour/hour minimum payable in advance via PayPal.
Out of state residents please post your questions on the FORUM for quick answers. Copyright 1995~2006 Expert Pool & Spa, Inc. All rights reserved.
No portion of this web site may be reproduced or copied without permission. Pricing, availability, content, advise, or technique may change without notice.
All content is provided "as is" and Expert Pool & Spa, Inc. is not responsible in any way for losses arising due to related content on this site.
Expert Pool & Spa does NOT sell or service aboveground pools. Try the FORUM for questions and answers!  This site is optimized for 1024x768 Resolution screens.
This website was last updated on
Tuesday May 24, 2011