how much chlorine to add to pool

A pool’s crisp, sparkling water turns a sweltering day into a delight. But a pool that isn’t properly maintained will end up murky and feel more like a dip in a swamp than the refreshing experience you had when you first filled it with water. One of the most important aspects of pool maintenance is proper chlorination. 

But many people aren’t sure how much chlorine to use in their pools. Amplifying this confusion is the number of chlorine options and chlorination delivery systems available. This post will clarify what you should look for in a pool chlorination solution and how much you should add to keep the right balance.

What Is Chlorine, Really?

The chemical substance known as chlorine is a household name. You’ve used it when doing laundry to keep your whites as white as the day you bought them. If you live in the city, you likely have chlorine added to your tap water to ensure that it’s sanitary for you to drink. 

Depending on the amount used, chlorine is either a powerful cleaner or an effective sanitizer. In your pool, it helps to serve both purposes. 

How Does Chlorine Affect Pool Water?

You may think chlorine’s role as a bleach for your clothing is the primary way it keeps your water nice and clear. While high doses of chlorine, such as pool shock, can serve to clear a murky pool quickly, the daily chlorine levels work more as a preventative measure. 

The murkiness of water comes from living things, such as bacteria and algae. Without the proper amount of chlorine, killing algae can become more difficult.

When set correctly, the chlorine level in your pool is enough to kill these organisms without negatively affecting your health. This prevents them from accumulating enough to dirty your pool or expose you to harmful bacteria.

Why is It Safe for Swimming?

If you buy a bottle of bleach for cleaning laundry or surfaces around the house, you’re supposed to dilute it and wear protective gloves when working with it. As we know it, chlorine is powerful stuff. But, as we mentioned earlier, there’s also a tiny amount of it in your drinking water, working to kill bacteria and keep you healthy. 

The key to chlorine’s safety as a pool additive is adding the right amount. We’ll discuss later how to ensure you don’t add too much.

What Types of Pool Chlorine Are There?

As you go out for supplies and look at the chlorine options, you’ll notice that the chemical comes in both stabilized and unstabilized forms. If you have an outdoor pool, as most are, it’s important that you understand the difference between the two.

  • Stabilized – Chlorine, like many other things, doesn’t particularly enjoy prolonged exposure to the sun. Just as you’ll get sunburned if you stay out too long without sunscreen, your chlorine will break down if it isn’t protected. Stabilized chlorine has an extra chemical that protects it from sun exposure. 
  • Unstabilized – It stands to reason that unstabilized chlorine does not have any protection from the sun. If your pool is indoors, this likely isn’t a problem as it will not be receiving a lot of direct sunlight. While you can use either type of chlorine in an indoor pool, you should usually only use stabilized options in the outdoor variety. 

What Is the 7.5% CYA Formula?

The stabilizer used in chlorine products is called cyanuric acid (CYA). In addition to being included in stabilized chlorine, this substance can form on its own when too much nitrogen or chlorine is in your pool or your pool’s filter isn’t doing its job effectively. 

The goal is to keep chlorine levels at around 7.5% of your CYA levels. So, if your test strip says that you have 40 ppm of CYA, you’ll want to keep the chlorine at around 3 ppm. Just as you can purchase unstabilized chlorine without CYA, you can buy CYA on its own. 

CYA is typically sold as a product known as a pool stabilizer. Purchasing them separately will make it easier to adjust the levels.

Do I Always Need to Stick With That?

Although the 7.5% CYA rule is a good guide, it shouldn’t be seen as something set in stone. The reason is that too much chlorine in your pool can be dangerous. If your pool has an exceptionally high CYA count, adding enough chlorine to get you to 7.5% CYA could result in unsafe conditions.

If you’ve ever been in a room where bleach was being used without being diluted enough, you’ve already experienced some of the health side effects of being exposed to too much chlorine. Although your pool won’t ever get to concentrations that high, you’ll still experience irritations of the skin, eye, and lungs if the levels get too far, about 5 ppm. 

Similarly, if CYA levels are quite low, shooting for 7.5% would mean insufficient chlorine in the pool. If your chlorine levels aren’t high enough, the chemical won’t be effective at keeping the pool clean and bacteria-free. 

In general, you want to keep your pool’s chlorine levels between 1-3 ppm. Although it’s safe to go a little higher, you should avoid letting your pool’s chlorine level get above 5 ppm.  

Why You Can’t Let the CYA Get Too High

Having too much CYA in your pool may result in you accidentally adding too much chlorine. But even if you’re careful to measure the amount of chlorine and wise enough to abandon the 7.5% CYA method if it’d put you over, there is still a reason not to let your CYA levels get too high. 

Too much CYA in your pool can decrease its pH and cause staining or scaling. Not only will it shorten the lifespan of your pool that way, but it will also reduce the effectiveness of the chlorine. 

What Are the Benefits of Different Chlorine Delivery Methods?

Now that you’ve determined what chlorine levels you should keep your pool at, it’s time to look at the various ways of adding it to the pool. There are two aspects to consider when adding chlorine to your pool: the form in which it will be added and the delivery method. Both of these aspects have essential factors to consider. 

Forms of Chlorine

Chlorine for pools comes primarily in three forms: granules, tablets, and liquid. In general, tablets are the preferred option for most pool owners. There are tradeoffs between the options, so granules may be the right option for some. Liquid is rarely used outside of commercial pools.

  • Granules – These are smaller in size and typically contain a lower chlorine concentration than tablets. This gives them the benefit of dispersing into the pool more quickly. Granules are also as easy to apply as tossing a measured amount into the pool. Because it’s easier to adjust the levels and the changes take effect more quickly, granules are preferred for those who have a pool that has varying maintenance needs. This could be from heavy rainfall or inconsistent exposure to the sun.
  • Tablets – Tablets are much larger; they look like hockey pucks and come in 1-inch and 3-inch sizes. As long as the needs of your pool stay the same, these are often the best option. They apply a consistent amount of chlorine to the pool. As long as your pool’s needs are consistent weekly, you’ll eventually learn how much to add each week and save yourself the hassle of constant measurements.
  • Liquid – Liquid chlorine comes in much higher concentrations and will raise the chlorine level of the pool more quickly. However, because of its high pH, care must be taken to add the appropriate amount of CYA to bring that value within the acceptable range. Liquid chlorine may also damage pool liners if used inappropriately. 

Types of Chlorinators

Although granules can simply be added to the pool, tablets require a delivery method. You have several different options for delivering chlorine to your pool water. The solutions get better as they get more expensive, but if you’re careful, each method will serve its role effectively. 

Let’s look at the options:

  • Floating chlorinators – The cheapest overall option is a floating chlorinator. This is exactly what it sounds like; a floating device into which you put the tablets. The idea is that the chlorinator will bob all around the pool as the wind and current do their thing. Unfortunately, these devices never move consistently across the whole pool and often get stuck in one spot.
  • Skimmer basket – Your pool comes built-in with a chlorine dispenser, sort of. The skimmer basket that gathers the debris as the water is sucked into the pump makes an excellent place to simply drop a chlorine tablet and forget it. As the pump runs, it will bring in the chlorine and distribute it back into your pool. As part of a moving water system, the distribution is fairly even. However, the pump must be running for the chlorine to flow, so electricity costs can add up. The high concentration of chlorine in contact with the skimmer basket will also cause its plastic to degrade more quickly than it otherwise would.
  • Automatic chlorinators – These devices also rely on your filter to distribute the chlorine. Instead of just dumping the tablets into the skimmer basket, automatic chlorinators are specially plumbed to the output jets of your pump. Tablets are placed in the chlorinator as in any other dispersal device, except automatic chlorinators allow you to set the desired chlorine level and forget it. As long as you keep the dispenser full of tablets, it’ll automatically distribute the right amount. 

Answered: How Much Chlorine to Add to Your Pool

Maintaining the proper amount of CYA and chlorine in the appropriate ratio is important to the longevity of your pool. More importantly, it’s vital to your health. Exposing yourself unnecessarily to harmful bacteria or chlorine levels is easily avoided with some care to the amounts of each being added to the pool. 

Chlorine alone won’t give you that pristine pool water everyone craves. A ProTuff skimmer net will get the larger debris out of the pool. Contact us to learn more about how our products can help keep your pool in its best condition.

Disclaimer: Pool ownership and maintenance is very complicated, and we know every situation is unique. While we’ve done our best to cover the best practices here, we encourage you to reach out to ProTuff directly at with any specific questions you may have.

How Much Chlorine to Add to Pool

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