Keeping your swimming pool clean and safe requires choosing the right pool chemicals, especially chlorine. Chlorine is the most widely used disinfectant in pool maintenance, including stabilized chlorine and unstabilized chlorine. Then what's the difference between them? In this article, we'll explain what these two types of chlorine are, their pros and cons, and how to choose the right type for your swimming pool.
What is Stabilized chlorine
Stabilized chlorine refers to those chlorine compounds that can hydrolyze to form hypochlorous acid or hypochlorite so as to maintain the pool water quality clean and hygienic. The stabilized chlorine does not contain hypochlorite, so it's very stable and has a shelf life of more than two years.
Common types of stabilized chlorine include:
Both are excellent pool chemicals, but we recommend SDIC because it not only has good security and a long shelf life, but also has little impact on the pool pH. Of course, if you have a huge swimming pool, such as a 1000m3 pool, using TCCA chemicals in feeders can be more convenient.
Besides, stabilized chlorine can be hydrolyzed to form cyanuric acid (CYA), also known as chlorine conditioner. Without CYA in the pool, HClO breaks down quickly under the exposure of sunlight, breaking down more than 90% of the free chlorine within 2 hours. CYA can form a protective shield to protect chlorine from rapid decomposition by the sun's UV rays, thus extending the life of chlorine in pool disinfection.
Benefits of Stabilized Chlorine
- A long shelf life
- Safe and convenient to transport, store and use
- Little irritation for swimmers
- Slower chlorine loss under sunlight exposure
- More stable sanitizer levels in hot weather
Considerations
However, long-term use of stabilized chlorine can increase the concentration of CYA in the pool, causing chlorine lock phenomenon. This results in less effective disinfection of the pool, which increases the risk of bacteria, viruses and algae growth.
You may like: How to Lower Cyanuric Acid in a Pool
What Is Unstabilized Chlorine
Unstabilized chlorine refers to those compounds that directly release hypochlorite to water. The common unstabilized chlorine products are calcium hypochlorite (Cal Hypo), sodium hypochlorite (NaClO), etc., which do not contain cyanuric acid.
Benefits of Unstabilized Chlorine
- Immediate and powerful sanitizing effect
- No buildup of cyanuric acid
Considerations
Cal Hypo is a common pool shock chemical used by many pool managers. But it has a big disadvantage, that is, it contains a lot of insoluble matter, which must be dissolved and clarified in advance, and then poured into the pool.
NaClO is cheap and convenient, but it has such a short shelf life that you can hardly be sure of its exact available chlorine content after a period of storage.
In terms of unstabilized chlorine, it has a short shelf life and poor security. Meanwhile, it must be used with CYA to avoid degradation by sunlight.
Best Practices for Using Chlorine Pool Chemicals
- Monitor CYA Levels: If using stabilized chlorine, keep cyanuric acid levels between 20-100 ppm.
- Balance Other Pool Chemicals: Ensure proper pH, alkalinity, and calcium hardness for maximum chlorine efficiency.
- Use Both Types Strategically: Use stabilized chlorine for routine maintenance and unstabilized chlorine for occasional shocking or indoor pools.
- Test Water Regularly: Use reliable test strips or pool testing kits to keep chlorine levels between 1–3 ppm.
If you would like to learn more, check out our ultimate guide to pool chemicals here.
In summary, stabilized chlorine and unstabilized chlorine have their own characteristics in disinfection of swimming pool. In practical applications, you should select appropriate disinfectant products according to the specific situation and needs of the pool, and the operation and management should be carried out in strict accordance with the instructions for use to ensure the safety and health of the pool water quality.
Looking for high-quality chlorine products? At Aquaenjoy, we offer a full range of pool chemicals, including TCCA, SDIC, Cal Hypo, cyanuric acid, pH regulators, algicides, clarifiers, etc., backed by 30 years of experience and global certifications.