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How To Balance Cyanuric Acid In Your Swimming Pool

Note: This post may contain affiliate links. This means that at no cost to you, we may receive a small commission for made purchases.

If you are a swimming pool owner, you probably understand the importance of keeping the chemistry of your pool’s water balanced and correct at all times.

This can be a confusing task sometimes as it requires a lot of knowledge on subjects that are not generally well known, and it might take some practice to get used to the right routine.

But it is all worth it in having a pristine pool perfect for swimming in. If you live in a particularly sunny area, this can make the task of keeping the pool water’s chemistry balanced even more difficult.

This is because the sun will absorb the chlorine from within your pool which will throw off the balance you are trying so hard to maintain.

This is why lots of pool owners use chlorine stabilizers to try and stop this from happening.

Many people think that simply adding a stabilizer is enough to stop the problem, but unfortunately, that is not the case. 

One of the most important things when stabilizing the chlorine in your pool is, correctly balancing your use of cyanuric acid. So what is this component, and how do we use it correctly?

What Exactly Is Cyanuric Acid?

A key ingredient in maintaining chlorine stability is Cyanuric Acid (also referred to as CYA) and it is known to be used as a chlorine stabilizer for pools as well as a pool conditioner.

It has a few different forms depending on the pool and the preference being used mainly in a powder or a liquid form, but it is also a key ingredient within other products like chlorine sticks and tablets (see also ‘Applying Chlorine Tablets In Your Pool: A Short Guide’) that are referred to as dichlor or shock.

When this ingredient is used in tablets or shocks it will form a substance known as stabilized chlorine which will not be needing any more stabilizer or the use of other chlorine products like sticks or tablets.

However, there are important reasons to consider when it comes to not overusing the substance.

If the CYA stabilizer accumulates until reaching harmful levels this can be called ‘creep’ and makes the pool water dangerous.

What Does A Chlorine Stabilizer Do?

How To Balance Cyanuric Acid In Your Swimming Pool

It is alarming the first time you learn that half of the chlorine in your pool can get destroyed by the sun’s UV rays in as short as 17 minutes.

Similar to using sunblock to protect our skin from the damage of UV rays, a chlorine stabilizer acts the same way for your pool.

The way the chlorine stabilizer acts is by binding to chlorite ions and will guard them from the damage of the sun.

And if this is not done and a stabilizer (see also ‘How To Add Stabilizer To Pool Without Skimmer’) is not present, the important chlorite ions will be torn apart and lead to the chlorine evaporating.

The stabilizer is stabilizing the ions, which is why it is named so aptly. The stabilizer is what helps chlorine stay in your pool for as long as possible enabling it to complete its job.

The role of chlorine is to stop the pool from becoming an area where harmful bacteria, as well as algae, can thrive.

So if the stabilizer is not protecting the chlorine, the chances of these consequences occurring is a lot more likely.

In spite of this, if you are extending the usage of your chlorine through the use of a stabilizer, some issues can occur.

The most prevalent of these issues is that the longer you stabilize chlorine in a pool, the less powerful the chlorine’s ability to sanitize is.

This means that the stabilized chlorine generally ends up taking a longer time to combat the effects of bacteria in comparison to an unstabilized chlorine.

But you can compensate for this if you manage to keep your stabilizer balanced and maintain healthy chemistry within your pool water.

How Much Pool Stabilizer Should You Use?

Before you start thinking about how much pool stabilizer you want to introduce to your pool, try to determine the amount of CYA that is already present in your pool.

Luckily there are two pretty easy ways of testing this. These methods include using testing strips which are easy to use and get quick results.

Or if you are willing to make more of an investment you could buy a pool monitor (see also ‘Best Smart Pool Monitoring System: Reviews & Buying Guide’) that will easily read the levels present of every chemical which is in your pool water.

The desired level of CYA you will want at this point in the process is somewhere between 30 ppm to 50 ppm.

However, if you are working with a saltwater pool the levels of CYA required a higher, this is why most saltwater pool experts will recommend trying to keep your CYA content between 60 ppm to 90 ppm.

As previously mentioned maintaining a balance is important, too much CYA and the chlorine will become less effective and will give you a pool with a cloudier green tinge.

But if you do not include enough CYA then your pool’s chlorine will break down very prematurely.

What Is The Ideal Amount Of CYA To Use?

As has been emphasized up until this point; getting a correct balance of CYA to your levels of chlorine is of utmost importance. 

The best free chlorine levels you will want are around 2 to 4 ppm, but extra considerations will need to be made. 

You will want the chlorine levels to stay around 7.5% of the CYA content if this is confusing, luckily there is a formula to make working this out easier.

Your CYA ppm worked out in the last section, multiplied by 0.075 is the free chlorine level you are working with.

For example, if your CYA level is 50 then 50 multiplied by 0.075 is 3.75 which will be your free chlorine level.

It is also worth noting that if you have CYA level that are above 100 you will have a hard time getting accurate results from standard pool testing strips and will need to contact a professional who can test up to 300 CYA levels.

What Will Cause An Imbalance Of CYA And Chlorine?

Using too much CYA is a lot easier than it might seem, and most people tend to use it without thinking and end up with excess CYA.

This is because most of the time you are adding chlorine to the water, it is likely that CYA will be going in with it as well.

As previously stated, chlorine like dichlor (see also our article on dichlor chlorine) or trichlor contains CYA to stabilize the chlorine, so you will have to take this into account.

The opposite is true for liquid chlorine that will nearly always not include a stabilizer so more CYA will be needed.

As with most things, it is easier to add more CYA than it is to get rid of it if you end up with too much.

So make sure to practice caution during this process as CYA can build up quicker than you imagine. 

Also keep in mind when water evaporates, the CYA does not, so make sure to take this into account when topping up your pool.

What Are Your Options If There Is Excessive CYA In Your Pool?

How To Balance Cyanuric Acid In Your Swimming Pool

If you have tested your pool, and you have noticed that your CYA levels are way higher than anticipated, and you need to get rid of some, there are a couple different methods you can try to lower it back down to what you need.

Partially Drain And Dilute Your Pool Water

The easiest way to partially drain a pool is to use a water vacuum (see also ‘How To Hook Up Pool Vacuum To Intex Pump’)
or to use your filter’s waste function.

And after this has been done, you will want to refill the pool with a fresher water. 

The best way to know how much to drain and refill your pool by is actually quite simple. If the CYA levels are 25% too high, drain and refill 25% of the water.

If it’s 5% too high, replace and refill 5%. Just follow this pattern based on your results.

After you have done this you will want to start running your water pump for a while (at least a few hours) to properly agitate the freshwater you have added back into our pool.

Once this is done you can test for your CYA levels and repeat the process if they need further adjustment.

If you used your filter to drain the water, and you had high CYA content, it is worth changing your filter to prevent the excess CYA flushing back into the pool.

Use A RO (Reverse Osmosis) Filter

There are specific filters that are made for the task of removing excess CYA from water but of course this is a lot more expensive than the first option.

However, they work best for those who have limited options on draining their pool, or do not have the time to carry out the whole process.

Should You Use CYA Reducers?

There are some products on the market that are advertised to act as CYA reducers and will work to decrease the CYA content in your pool.

However, these products rarely work as well as advertised. They also tend to work quite slowly so actually seeing results can take longer than a week sometimes.

While they are good if it is your only option, the previous two methods will be much more efficient and effective.

How To Use A Pool Stabilizer?

When you are adding a stabilizer to your water supply, taking all the correct safety precautions is of vital importance.

The stabilizer is in essence, an acid, and this acid can be damaging to your skin, and your pool if it is used incorrectly. 

The first precaution to take is to make sure when working that you have goggles, and gloves on. 

While some stabilizers will advise putting the stabilizer in the filter or just straight into the pool, there are safer ways to do this.

If you have a fiberglass or vinyl liner pool (see also ‘ How To Easily Patch Any Vinyl Pool Liner ‘), it is recommended that you dissolve your stabilizer into a large container of warm water.

The best strength level to go with is to ad 13oz of stabilizer to get a desired CYA of 10 ppm within a 10,000 gallon capacity swimming pool.

You will want to carefully put this solution in the water from the edges of the pool to avoid causing any damage.

If you are working with a concrete pool, dissolving will not be necessary and put it right into the pool where it is best to disperse the stabilizer using something like a brush.


Now you know the importance of Cyanuric acid within swimming pools and why balancing it is so important.

Make sure to check the chemistry of your pool regularly to make sure it will not need changing!

author avatar
Anthony Barnes
Anthony Barnes is the founder of Water Heater Hub and a second-generation plumber by profession. Before developing Water Heater Hub, Anthony Barnes was a full-time plumber, and he has undertaken a wide variety of projects over the decades. As a second-generation plumber, it was easy for Anthony to get used to the technicalities of all from a tender age


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