Yes, pools need CYA (cyanuric acid) to protect chlorine from UV degradation. Target 30-50ppm for regular pools and 70-80ppm for salt water generators.
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Yes, your pool absolutely needs CYA (cyanuric acid), also called stabilizer or conditioner. Without it, the sun's UV rays will destroy your chlorine within hours, making it nearly impossible to maintain proper sanitization levels and wasting money on chemicals.
Before determining what action to take, you need to identify your current CYA status and pool type:
Use a reliable test method to measure your existing CYA. The Taylor K-2006C test kit provides the most accurate readings using the turbidity method. Pool test strips are notoriously inaccurate for CYA testing and should be avoided for this critical measurement.
If you don't have a proper test kit, take a water sample to a pool store, but specify you want a CYA test - many basic tests don't include it.
Cyanuric acid forms a weak bond with free chlorine, creating a protective shield against ultraviolet rays. Without this protection, a properly chlorinated pool can lose all its sanitizing power in just 2-3 hours of direct sunlight. This explains why some pool owners struggle with constant algae problems despite adding chlorine regularly.
Properly stabilized pools use significantly less chlorine. A pool with 40ppm CYA will retain chlorine 8-10 times longer than an unstabilized pool, translating to substantial chemical cost savings over a swimming season.
CYA and free chlorine work together in a specific ratio. Higher CYA levels require proportionally higher chlorine levels to maintain effective sanitization:
Salt water generators work more efficiently with higher CYA levels (70-80ppm) because the constant chlorine production compensates for the higher minimum chlorine requirements.
Add stabilizer immediately using these dosing guidelines:
For granular stabilizer, pre-dissolve in warm water or add directly to skimmer with pump running. Full dissolution takes 24-48 hours, so retest after this period.
Calculate the difference between your current level and target level, then dose accordingly. For example, if you have 20ppm and want 40ppm in a 15,000-gallon pool:
(40-20) × 15,000 ÷ 10,000 × 13 ounces = 39 ounces of granular cyanuric acid
Maintain current levels through regular testing. CYA doesn't degrade from sunlight or normal pool operations, so levels remain stable unless you drain water or experience heavy rainfall overflow.
The only way to reduce CYA is dilution through partial water replacement. Calculate the percentage of water to replace:
Water replacement % = (Current CYA - Target CYA) ÷ Current CYA × 100
Warning: Trichlor tablets and dichlor shock contain cyanuric acid. Using these products exclusively will cause CYA to climb above optimal levels over time. Balance your sanitization approach by using unstabilized liquid chlorine for daily dosing and save stabilized products for specific applications.
Add CYA early in the startup process, ideally before or immediately after achieving proper pH and alkalinity balance. This prevents chlorine waste during the initial sanitization phase.
CYA becomes more critical during peak sun months (May through September). Pools that seem fine in spring may struggle with chlorine loss as UV intensity increases through summer.
Test CYA levels monthly during swimming season and after any significant water dilution events. Unlike other chemical parameters that require frequent adjustment, CYA typically remains stable for extended periods.
Retest 48 hours after any CYA additions to verify dissolution and proper levels before adjusting chlorine targets accordingly.
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