How Sunlight Can Affect The Chlorine In Your Swimming Pool

A person holding a pair of gloves next to a pool exposed to sunlight.

Your pool is a great place to relax and let go of all your troubles. A dip in your pool and get rid of the stress that you have been harbouring lately. It helps you relax and make amazing memories with your family.

Not only that, a pool can be the centrepiece in your backyard that ties in the aesthetic of the place. You can also host parties and barbecues and invite people over. It is a great way to socialise and a pool is a great conversation starter too.

But owning a pool is and maintaining it is not a walk in the park. You will have to be regular in its maintenance, and any slacking can lead to some messy situations. It is best that you read up all you can on taking care of a pool and prepare yourself.

Maintaining a pool can be easy if you do it regularly. All you need to do is dedicate a few hours a week and your pool will be in great condition no matter what. From skimming the pool to backwashing the filter, a little effort goes a long way.

Chlorine levels and sun

Chlorine acts as a disinfectant and protects your pool from the buildup of organic matter. It is especially useful against algae and bacteria as they can change the colour of the pool and make it unusable.

Chlorine is also the main cleaning agent in bleach, but that does not mean you start using bleach in your pool. If you have money to burn, this can be a great solution, but buying chlorine would be far more cost-effective.

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Chlorine and the sun have a multifaceted relationship. When it comes to chlorine content, being exposed to the sunlight can actually be disastrous for your pool.

Chlorine content

In your pool’s ecosystem, there are two types of chlorine; free and combined. Free chlorine is the percentage or fraction of chlorine that is available to act as a disinfectant.

The free chlorine is the one that acts on algae and bacteria and makes them inert in the pool’s ecosystem. High levels of combined chlorine mean that there is an invasive species in the pool. Your pool water will lose colour and will be cloudy if such is the case. If your pool starts to look murky, it is best that you shock the pool with chlorine.

Shocking the pool means that you introduce a chlorine spike in the pool that gets rid of all the organic matter that might be festering in the pool. The sudden increase in chlorine makes the pool unusable for a few hours, so you must wait before you start using it again.

Temperature and chlorine

Higher temperatures can break down the chlorine and render it ineffective. Add to that the fact that bacteria and algae grow best in warmer conditions, your pool can become a serious health hazard in a matter of hours.

The hypochlorite ions are also known as the free chlorine that is available in the pool. It curbs the organic matter and does not let algae and bacteria grow in your pool system.

Warm water can be troublesome for you and your pool’s system. Not only will the water evaporate at a faster rate, upsetting the chemical balance of the pool, the warm water is also a better breeding ground for bacteria. This makes it tough to use the pool and you will have to add more chlorine to the pool.

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As a rule of thumb, for temperatures above 26 degrees celsius, you will have to double the amount of chlorine that you are using every 10 degrees or so. This is the only way that you will have a clean pool with enough chlorine to kill off any organic matter.

Cyanuric acid

It is used to prevent chlorine loss as it protects the free chlorine from being destroyed by UV rays. It acts as a conditioner or a stabilizer and can make your pool’s ecosystem much more stable than before.

If your pool is exposed to sunlight, then we recommend adding cyanuric acid to the pool. It acts as a stabilizer and helps you contain the chlorine loss that happens. It makes sure that there is enough chlorine in the pool, which in turn makes sure that there is no algal or bacterial growth.

Inground fibreglass pools exposed to direct sunlight should have 60-80ppm of cyanuric acid in their systems. In extreme cases, you can up to 100ppm, but always check with a pool expert for what would be suitable for your pool. Routine testing is a great way to determine chemical levels in your pool, and you should do it at least once a week.

If there is too much cyanuric acid in the pool, there is a chance that your chlorine might not be as effective. Higher levels of cyanuric acid make the chlorine bind with the acid itself, which hampers the disinfectant properties of the pool. Higher levels of the acid will also make the pool water cloudy. You will have to replace the water as there is no other way of reducing the concentration of cyanuric acid in the pool.

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UV rays and chlorine

The sun’s rays not only just evaporate the water in the pool, but the UV rays also cause the chlorine in the water to break down and dissipate. When exposed to constant sunlight, chlorine can easily lose its efficiency in such an environment. In such cases, you should invest in a pool cover.

The dissipated chlorine cannot be reclaimed, and you will have to add more chlorine to the pool. This makes pool maintenance hectic for both new and experienced owners. To avoid such things, a normal pool cover would do the trick.

We recommend you get a hardcover or an automated one so that your pool area is not a hazard for pets and children. It is very easy to get tangled in a soft pool cover. A hard one can take the weight of your kids and pets. It will also make the pool area not useless as you can carry out normal activities over the pool.

Getting a hardcover is great as it will also protect your pool on windy and rainy days. Both of these combined with the UV rays can spell disaster for your pool’s chemistry.


This way, you can have a stable equilibrium when it comes to the chemical state of your pool and also have usable water no matter what the weather is. Ask your neighbours and experienced pool owners as to how they maintain their pools. They will be able to give you solutions according to your area.

If you ask around enough, our name will surely come up. We are some of the best pool experts in the area and will be more than happy to help you out with your pool-related needs.

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Our experts will be more than happy to answer all your questions and clear all your doubts. Contact us and we will get rid of all your pool-related dilemmas. Our experts will come on-site and give you the best solutions for your problems. We will also give a great deal on the services and we have a great customer service record to back our claims too.

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