Swimming Pool Chemical Guide: Water Chemistry Explained

Pool Chemistry Guide

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Wouldn’t it be great if all you hard to do once you get a pool was to fill it with water and forget about it? Well, this would save you a lot of time and effort in maintenance but unfortunately, owning a pool comes with lots of responsibilities such as maintaining good water chemistry.

Together with sanitization, maintaining the right chemistry for your pool water will ensure it is clean and safe enough for the swimmers. In turn, this ensures the swimmers enjoy the water more and look forward to regular dips.

But, to keep your pool in great shape, whether it is as standard chlorinated or saltwater one, you need to understand what pool chemistry is all about and the factors that affect your water balance.

Why is Pool Chemistry Important? 

Pool chemistry is all about monitoring different pool water chemicals to ensure you maintain the right levels, and that there is a perfect balance between them. Here are some reasons why it is crucial.

1. Pool Water Safety and Comfort: The main reason why maintaining proper pool chemistry is essential is that it will determine the safety and comfort of your pool water. If any of the chemicals are too high or low, skin and eyes will suffer a lot when swimming. Worse yet, an imbalance leaves the water dirty and teeming with germs and bacteria, which increases risks of infection for swimmers.

2. Surface and Equipment Corrosion: A pool and all the equipment that come with it are quite expensive, and so to protect your investment, you need to keep the water chemistry balanced. An out of balance chemistry can result in corrosion of surfaces, handrails, ladders, and other equipment and hence damaging your expensive investment.

3. Scaling and Staining: The right pool chemistry is vital for maintaining the aesthetic appeal of your swimming pool. And this is because if it is out of balance, it can lead to scaling and staining of the surfaces, which leaves you with an unsightly pool.

4. Algae Formation: Algae is perhaps one of those things that every pool owner dreads seeing their pool as, besides making the water uninviting, it is a perfect breeding ground for germs and bacteria. Maintaining pool water chemistry balance is one of the best ways to prevent algae formation.

Chemical Factors That Affect Water Balance

Chemical Factors That Affect Water Balance

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There are four main chemical factors that you will need to watch out for to ensure that you maintain proper water chemistry and balance, which are pH, alkalinity, calcium hardness, and cyanuric acid.

1. pH

pH measures the acidity or basicity levels of the pool water. The recommended pH level for pool water is 7.4 to 7.6, but anything from 7.0 to 7.8 is still acceptable for many pools as the water will be safe and comfortable enough for swimmers.

Different things can cause changes in the pH of your pool water, such as dirt, leaves, rain, and anything else that enters your pool. Sanitizers also affect pH levels. Chlorine tablets often cause a fall in pH, while liquid chlorine leads to an increase.

If the water pH is too high, it will cause scaling on the pool’s surface and plumbing system. (Read More: How to Lower pH of Pool).

While a too low pH leads to erosion of metal fixtures and etching on the sides. (Read More: How to Raise pH in Pool).

Hence, it is essential always to have pH degreasers and increasers to keep the level optimal.

2. Total Alkalinity

The total alkalinity of pool water measures the carbonates, alkalines, and hydroxides. It is closely related to pH, and one of its primary functions s to ensure the latter remains stable.

Total alkalinity that is too low leads to unstable and erratic pH levels, and if it is too high, the pool water becomes cloudy, and the pH starts to drift upwards. When you need to raise alkalinity, sodium bicarbonate is always the chemical of choice. However, the same acids used to lower pH will be perfect for lowering alkalinity.

Total alkalinity is measured in ppm (parts per million), and for most swimming pools, the desired range will be between 80 and 120 ppm.

Note: The total alkalinity will not determine the pH levels in your pool water but will act to ensure it remains in the desired range.

3. Calcium Hardness

Calcium hardness is the sum of all the calcium dissolved in the pool water, and it is a measure of the hardness or softness of the water. Hence, for your pool water, it depends on factors like where you live and the source if your water.

Water hardness of between 100 and 400 ppm is ideal for most pools. If it is higher than this, the water becomes too hard, and it can also be too cloudy, which makes swimming unpleasant. Low levels, on the other hand, make the water feel slimy and cause corrosion of pool surfaces.

Adding calcium chloride, which is also often referred to as a hardness increaser, is the best way to raise the calcium hardness levels in your pool. But when it comes to lowering it, there is hardly any better way than draining and diluting with soft water.

Read More: How to Remove Calcium Scale from Pool

4. Cyanuric Acid

Cyanuric acid or CYA is added to pool water to help minimize the degradation of chlorine, which often occurs when the water is exposed to the sun. By adding this compound, the effectiveness of the chlorine at cleaning the water is maintained for longer, and hence minimizing the frequency of adding more, which translates to reduced maintenance costs.

The levels of cyanuric acid in pools water is measured in parts per million, and anything between 30 and 50 ppm is often recommended, but up to 100 ppm is still safe. Anything above this hurts the water balance and affects the effectiveness of chlorine in cleaning pool water.

For lower levels, you will need to add more cyanuric acid to fix the problem. Dilution or using a cyanuric acid reducer will help you lower levels over 100 ppm.

Maintaining Clean Pool Water

Maintaining Clean Pool Water

Maintaining clean pool water takes dedication, effort, and time. Here, there are 3 crucial elements of keeping the pool water clean, which are sanitizing, shocking, and keeping algae growth in control.

1. Sanitization

Sanitization is the process of controlling bacteria and germs in your pool, and it is a crucial part of regular maintenance that you cannot escape regardless of the swimming pool type or size.

Here are the most common compounds that you can use to sanitize your pool.


Chlorine is the most widely used and perhaps also the most critical sanitizer. It comes in both granular, tablet, and liquid forms.

The most commonly used options are sodium hypochlorite, discolor, tricolor, and calcium hypochlorite. Regardless of which form of chlorine you use, make sure you keep the levels between 1 and 3 ppm.


Like chlorine, bromine is also from the halogen chemical family. While it might not be as popular as chlorine, bromine is often preferred when you want to avoid the strong chlorine smell.

Bromine is best used in indoor pools and hot tubs as it does not do well when exposed to sunlight. Ideal levels of bromine in pool water are between 3 and 5 ppm.


While biguanide is also a highly effective chlorine-alternative, it is more expensive. This non-Halogen compound does not have the chlorine odor or irritations, and it is relatively stable, which minimizes the frequency of top-ups and testing. You should keep the levels at 30 to 50 ppm when using this compound.


Minerals provide a more natural way to sanitize your swimming pool. This sanitizer will contain copper or silver, which are natural algae and bacteria deterrents.

But, because minerals are not entirely effective at keeping bacteria and algae at bay on their own, you will still need to use a small amount of chlorine (about 0.5 ppm).


Ozone, which is active oxygen, has been in use for drinking water purification since the 1800s, but over the years, it has been catching on as an effective pool water sanitizer. What makes it an ideal chlorine alternative is that it does not irritate the skin and will also not have a strong odor.

But, given that ozone has a shorter life in water, you will still need trace amounts of a backup sanitizer like chlorine to ensure sanitization of all water molecules.

2. Pool Shock

Shocking your pool is super-chlorinating it with higher than usual doses of chlorine. The aim of adding the excess amounts of chlorine is usually to get rid of algae, chloramines, and contaminants. But, you can also do it for other reasons such as remove surface stains.

You can shock both chlorinated and saltwater pools, and the amount of chlorine that you will need depends on the combined chlorine levels in your pool water. Typically, you should add about ten times the level of combined chlorine.

While pool shock provides one of the most effective ways of cleaning pool water, it has some drawbacks. These demerits include the risk of causing water chemistry imbalance if not done correctly and difficulties telling the exact amount of chlorine to add.

3. Algae Control

The presence of algae in your pool water is one of the surest signs that there is something wrong with the water, and you need to do something. Besides making your water murky, algae will also throw the pool chemistry off balance, which worsens the situation.

Super-chlorination provides one of the most effective ways of controlling algae, and it can be useful for all three most common types, which are green, yellow, and black algae. However, vacuuming your pool manually and using an algaecide are also effective ways of controlling algae.

Safety Tips for Handling Chemicals

Safety Tips for Handling Chemicals

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  • Please Read and Understand Directions/Instructions: All those words at the back of a pool chemical package, be it chlorine, cyanuric acid, or algaecide, can be quite boring to read. However, it is crucial to ensure that before you use the stuff, you read and understand the directions. These directions not only explain how to handle the product safely but also what to do if there is accidental ingestion or touch.
  • Store the Chemicals Safely: It is vital to make sure that you store your pool treatment chemicals safely away from the reach of pets and kids. Treat these products with the same level of caution as medication and toxic compounds.
  • Only Use the Recommended Dosage: No matter what your opinion might be about the dosage, it is crucial to make sure that you only use the recommended dosage. Using too much of the product will not make your water cleaner. It will only affect the balance and make it unsafe.
  • Wear Protective Clothing: When handing chemicals, you need to make sure that you have protective gear. This often means wearing gloves, safety glasses, and protective clothes, or those that you do not mind if they get ruined.
  • Do Not Pour the Chemicals down your Drain: When discarding the pool chemical, you should not pour them down your drains as this can ruin your plumbing system and lead to expensive repairs.
  • Clean Up After Handling Chemicals: After handing any pool chemical, it is essential to make sure that you not only wash your hands with soap and water but also wash the rest of your body to get rid of chemical residues.


As a responsible pool owner, you need to understand pool chemistry as this will help you keep it in the best shape and make it as comfortable and safe as possible for your family.

That said, you should always start by knowing the optimal levels of essential factors like pH, alkalinity, and calcium hardness. Also, it is crucial to understand how to test them and how to reduce and increase them to the ideal level when necessary.

Once you understand this and know how to keep the pool water clean, you can be confident of getting the best service from it and also protecting your expensive investment.