Maintaining clean pool water involves a careful balance of various chemical compounds. Understanding their purpose and interaction is important for effective pool maintenance. Sanitizers are essential for killing bacteria and algae, but their chemical behaviors can be confusing for pool owners.
Understanding Sodium Dichloro-s-Triazinetrione
Sodium dichloro-s-triazinetrione, commonly known as “dichlor,” is a widely used granular chlorine product for pools and spas. It functions as a stabilized chlorine source, protecting chlorine from degradation. Dichlor rapidly dissolves, making it a convenient choice for routine chlorination or shock treatments.
Upon dissolution, dichlor releases hypochlorous acid, the active form of chlorine responsible for disinfecting the water. This active chlorine destroys harmful pathogens, bacteria, and organic contaminants, keeping the pool water safe. Dichlor also has a near-neutral pH, which helps minimize pH fluctuations after application.
Understanding Cyanuric Acid
Cyanuric acid (CYA), often called chlorine stabilizer or pool conditioner, plays a role in outdoor pool chemistry. Its primary function is to protect chlorine from the sun’s ultraviolet (UV) rays. Without CYA, UV radiation can quickly break down chlorine molecules, leading to rapid chlorine loss and reduced sanitizing power.
CYA forms a weak, temporary bond with free chlorine, acting like a “sunscreen” that shields it from UV degradation. This protection extends the effectiveness of the chlorine, allowing it to remain in the water longer to combat contaminants. However, high levels of CYA can diminish chlorine’s efficiency, slowing its ability to sanitize and oxidize, and potentially leading to issues like cloudy water or algae growth.
The Direct Link: Dichlor’s Contribution to CYA
Sodium dichloro-s-triazinetrione (dichlor) is chemically structured to include cyanuric acid. Dichlor is a chlorinated isocyanurate, meaning cyanuric acid is an integral part of its molecular composition. When dichlor dissolves in pool water, it releases both active chlorine and cyanuric acid simultaneously.
Every time dichlor is added to a pool, it directly contributes to the pool’s CYA level. For approximately every 10 parts per million (ppm) of free chlorine delivered by dichlor, about 9 ppm of cyanuric acid is also introduced into the water. This continuous addition can lead to a gradual accumulation of CYA over time.
Managing Cyanuric Acid in Pools
Managing cyanuric acid levels is important for maintaining balanced and sanitary pool water. Regular testing of CYA levels is recommended, especially when using stabilized chlorine products like dichlor. For residential outdoor pools, the optimal CYA range is 30 to 50 ppm.
If CYA levels become too high (exceeding 50 ppm), the chlorine’s sanitizing efficiency can be reduced, even if free chlorine levels appear adequate. The primary method for lowering excessive CYA is dilution. This involves partially draining and refilling the pool with fresh water.
While some commercial CYA reducers exist, dilution remains the most reliable strategy. Preventing high CYA levels is easier than correcting them, emphasizing monitoring and adjusting the use of stabilized chlorine products. Maintaining appropriate CYA levels ensures that chlorine can perform its sanitizing function efficiently, protecting the pool from contaminants.