What’s the Difference Between Stabilized and Unstabilized Chlorine?

The most important chemical in a pool is chlorine. Being the primary disinfectant in your pool water, having the proper chlorine levels will keep your pool clean and safe. There are several different types of chlorine that can be used in your pool and one of the main decisions you’ll need to make is choosing between stabilized and unstabilized chlorine.

Let’s dive into the differences between stabilized and unstabilized chlorine and discuss which one you should use.

Main Takeaways

  • Stabilized chlorine contains an additive, like cyanuric acid, that stops the chlorine from breaking down under the sun’s UV rays. Dichlor and trichlor are stabilized chlorine.
  • Unstabilized chlorine contains no such additives and is the better option for indoor pools.
  • Stabilized chlorine is best for outdoor pools, but make sure to keep an eye on the cyanuric acid levels.

What is Stabilized Chlorine?

Stabilized chlorine is a pool product that, due to its chemical bonds, does not break down when exposed to sunlight. Usually, an additive, like cyanuric acid, is added to the chlorine to make a stabilized chlorine compound. Using stabilized chlorine will allow you to change the chlorine content less regularly.

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Stabilized chlorine is helpful for outdoor pools that get direct exposure to sunlight. Due to the sun’s ultraviolet rays, unstabilized chlorine will break down after a long enough exposure. Sunlight exposure will lead to a less chlorinated pool, which means a less disinfected pool. Stabilized chlorine fixes that problem. The cyanuric acid added to the chlorine creates a compound not affected by the sun’s rays, thus not allowing the chlorine to escape the swimming pool.

Compounds such as dichlor and trichlor are examples of stabilized chlorine compounds. Trichlor has a much higher level of chlorine in comparison to dichlor, but your choice of which exact product to use will ultimately rely on the specifics of your pool. If your pool has no algae problem, then trichlor will likely work for you, but dichlor can better help with algae problems.

What is Unstabilized Chlorine?

Unstabilized chlorine is just chemical chlorine with no additives. The common additive in stabilized chlorine, cyanuric acid, is not present in unstabilized chlorine. This means that if the pool gets exposed to direct sunlight, the chlorine inside will react to the sunlight and break down.

Unstabilized chlorine is effective for use in indoor pools. Due to the lack of direct sunlight, the problem of chemical breakdown is averted. Using unstabilized chlorine for outdoor pools is not recommended because it will break down very quickly, rendering the chlorine’s disinfectant properties useless.

Unstabilized chlorine products require more maintenance to make sure chemical levels stay regular. This maintenance requires daily measurements of chemicals. You’ll want to monitor the chlorine levels on days when you use your pool heavily. Adding or balancing the chlorine content is essential for anyone using unstabilized chlorine.

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Key Similarities and Differences

Stabilized and unstabilized chlorine help disinfect pools, but finding the most efficient chemical will lead to fewer chores in the long run. Depending on the sort of pool you have, including whether it’s an indoor pool or not, the type of chlorine you choose should lead to a more efficient disinfecting routine.

Stabilized chlorine has the additive cyanuric acid. Cyanuric acid bonds with the chlorine compound, changing the chemical composition. Although it has the same ability to disinfect that unstabilized chlorine does, the bonds on the stabilized chlorine reduce chlorine’s overall practicality as a disinfectant.

The problem with stabilized chlorine is only noticeable when you add too much cyanuric acid to the pool. Too much cyanuric acid in your pool makes the acid bind with all of the chlorine, creating an environment ripe for bacteria growth. Free chlorine holds disinfectant properties, so if it’s not present due to an abundance of cyanuric acid, the pool will not be able to stay clean.

Having cyanuric acid levels that are too high is one of the biggest problems a pool owner can face. Cyanuric acid never breaks down, meaning it accumulates in the pool. This accumulation will lead to less and less effective chlorine over time. The only way to fix this issue is to partially or fully drain the pool, adding new, fresh water and unstabilized chlorine until you have the right chemical balance.

Managing a pool’s chemical content is more straightforward with stabilized chlorine because it loses less chlorine on a daily basis. Less chlorine loss means you won’t have to continually add or balance your pool’s chemical content. Unstabilized chlorine is recommended for indoor pools, but you will still need to check chemical content regularly.

The main issue with unstabilized chlorine is the loss of chlorine due to environmental factors. The ultraviolet rays from the sun break down the chlorine in your pool, allowing it to escape and reduce your pool’s chemical content. Chlorine breaks down due to sunlight, leading to a lower chlorine content in your pool, making keeping the pool clean more difficult.

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Which One Do You Use?

Stabilized chlorine is the best choice for outdoor pool owners. Due to stabilized chlorine’s ability to withstand the sun’s ultraviolet rays, it can last longer with less oversight in an outdoor environment. If you have the right mixture of chlorine and cyanuric acid, your pool will stay clean with little effort on your part. Just test the pool water and add as needed.

Unstabilized chlorine is recommended for indoor pools because it is better at disinfecting your pool, but only when not exposed to direct sunlight. The ultraviolet rays will break down the chlorine, leaving your pool needing more chlorine. But overall, unstabilized chlorine is better for indoor pools because it has more free chlorine to disinfect the pool.

That’s about it! If you’re looking for other pool care tips, make sure to read my guide on swimming pool maintenance.

Have chlorine questions? I’m here to help! Just shoot me a note.

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