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Water Care Advice

Pool Chemistry 101

Pool Chemistry 101

The warmer weather is approaching, and that means that pool season is finally here. It's time for pool owners across the country to start opening their pools and doing all the fun pool chores needed for a successful summer of refreshing recreation. Every pool care checklist must include one of the most important tasks of all — keeping up with the water's chemistry. 

Understanding pool chemistry is essential for a healthy, inviting pool. It can also keep you and your family safer while swimming all summer long. Below, learn more about the main chemicals needed to balance your pool water, the factors that can disrupt your pool's chemistry and how you can better stay on top of your pool's chemistry for your easiest summer of pool care yet. 

List of Pool Chemicals and What They Do

Pool chemistry refers to the chemical condition of your pool's water at any given time. Maybe in a perfect world, you could fill up your pool with fresh water and forget about it. But in the real world, countless external factors get into your pool water, dirtying it and making it an unpleasant sight to behold. 

You have to add chemicals to your pool to keep it clean, safe and beautiful. As a pool owner, you should know these chemicals by name and understand what they do to make the right decisions for your pool's chemistry. 

Below are some of the main pool chemicals divided into helpful sections based on their function. 

1. Sanitizers

Sanitizers are some of the most important chemicals you can use in your pool. They're absolutely essential, as they're the main ingredient that keeps your pool water clean and safe. Sanitizers stop health risks like bacteria, viruses, algae and other unwanted pollutants from having free rein over your pool's water. They're critical in keeping your pool water looking good, too. 


Chlorine is the most common type of pool sanitizer. As an oxidizer, chlorine enters the water contaminants molecules and destroys them from the inside. Chlorine is an excellent choice for removing bacteria, viruses and algae, and it can even prevent algae from appearing to begin with. The Centers for Disease Control and Prevention (CDC) recommends a free chlorine content of 1 part per million (ppm) in your pool water. 

There are two main types of chlorine to choose from:

  • Stabilized chlorine: Stabilized chlorine contains cyanuric acid. The sun's rays decompose the active chlorine in your pool, rendering it ineffective. The cyanuric acid protects the chlorine, allowing it to stay effective longer, even with the sun beating down on it all day long. This means you'll save money by avoiding having to add more chlorine as often. Note that too much cyanuric acid in your water can make the chlorine less effective, so you have to strike the right balance. 
  • Unstabilized chlorine: Unstabilized chlorine lacks cyanuric acid, making it less effective at cleaning your water after extended exposure to sunlight. This also means unstabilized chlorine will avoid the potential downfall of decreased potency that cyanuric acid brings. If you have an indoor pool, unstabilized chlorine could be a great option for enjoying the benefits of chlorine without the concerns of added cyanuric acid. 

You can also add cyanuric acid yourself for more control over your pool's chemistry. Be sure to read the information on your stabilized chlorine or cyanuric product packaging to avoid accidentally raising the pool water's cyanuric acid levels too high. 



Bromine may be the most popular chlorine alternative for pool sanitization. It sanitizes through ionization, breaking apart the molecular bonds of pool water contaminants. According to the CDC, the bromine level should be 3 ppm if you use it as pool sanitizer. 

Some people prefer bromine over chlorine because it has a longer active life after you add it to the water. After adding bromine to your pool, it sanitizes the water without the need for added bromine longer than chlorine would sanitize before needing more chlorine. 

Most bromine products contain small amounts of chlorine for added sanitizing power.


The pool chemical biguanide originally started as a surgical disinfectant similar to hydrogen peroxide. It's chlorine-free, which may be a positive for people sensitive to chlorine and its byproducts. It's also more expensive than chlorine and bromine.

Biguanide works by forcing small contaminants together into larger clumps that resist dissolving into the water. After clumping, the contaminants are a better size for your pool's filter to grab and remove them from the water. Unfortunately, this can contribute to more frequent filter clogs. 

2. pH 

A substance's pH level is a measure of its acidity or basicness. Measuring your pool water's pH is essential for having the best experience possible while making caring for your pool easier over time. 

The pH scale ranges from 0 to 14, with 7 being neutral. Anything below 7 is acidic, and anything above 7 is basic. The CDC recommends a pH level of 7.2 to 7.8 for residential pools. 

If you need to increase or decrease your pool's pH level, the answer is simple — use a pH increaser or a pH decreaser. These products will help you achieve the ideal pH level for your pool for safe, clean swimming.

Dialing in the right pH for your pool water might take some trial and error, and you may have to start slow. With dedication and commitment, you can reach that ideal pH range for your pool. 

3. Alkalinity


Alkalinity refers to your pool water's ability to resist sudden spikes or dips in its pH level. In other words, alkalinity is like a buffer for your pool water, keeping it more stable and balanced throughout pool season regardless of what the summer throws at it. The CDC recommends an alkalinity of 80 to 120 ppm in pool water for the best results. 

To get the best alkalinity level for your pool, you have two main product options:

  • Baking soda: Baking soda is a common chemical you can buy from the nearby grocery store, but you can also get large quantities of it from specialty pool stores. Pour it into your water little by little and test the alkalinity to see the results. 
  • Alkalinity increaser: You can also buy alkalinity increaser if your pool water's alkalinity is too low. Alkalinity increaser also increases pool water's pH. There aren't any alkalinity decreasing products on the market, but pH decreaser will also decrease your pool's alkalinity if need be. 

When adjusting alkalinity, it's important to start slow and take many chemical measurements to avoid overcompensating. If alkalinity is too high, try adding pH decreaser to lower both the pH and alkalinity. Add pH increaser to get the pH back to its ideal spot after hitting the right alkalinity. It's definitely going to be a balancing act that will take time and practice to get right. 

4. Calcium Hardness

Calcium hardness is the measure of how soft or hard your pool water is. Where you live and where you get your water greatly impact the pool's calcium hardness. For instance, well water is often hard, which means it has a high concentration of minerals, including calcium. If you use that same well water to fill your pool, you'll be dealing with pool water with a high level of calcium hardness. 

The CDC recommends a calcium hardness level between 200 and 400 ppm. Maintaining this range is crucial, as dipping below 200 or above 400 can have consequences you want to avoid. 

If your pool's calcium hardness is too low, water may begin leeching minerals from your pool surfaces, which contributes to corrosion. If your pool's calcium hardness is too high, your water can turn cloudy and start dumping the excess minerals on your pool surfaces. This leads to a white film on pool surfaces, known as scale.

Achieving the recommended calcium hardness range gives you the best chance of avoiding these unwanted outcomes. Use a calcium hardness increaser if your level is too low, or remove some water and add soft water to your pool if your calcium hardness is too high. 

5. Other Common Pool Chemicals

Other Common Pool Chemicals

As a pool owner, you may use — or are interested in using — various other pool chemicals. Here are some other tools to help you care for your pool, along with some other pool substances you should know about:

  • Pool shock: Shocking your pool is the act of super-chlorinating the water, or adding more chlorine than you normally would. Plan to shock your pool about once a week or whenever your pool becomes dirty or gets heavy use. Buy pool shocking products to make this part of the process easier. You should shock your pool several hours before using it to avoid overexposure to chlorine.
  • Chloramines: Chloramines are a byproduct of using chlorine to sanitize your pool. After chlorine's active life ends, it leaves behind chloramines that give off an unpleasant “pool” smell, sting the eyes and irritate the skin. They also reduce chlorine's effectiveness. The only way to get rid of chloramines is to add more chlorine to your pool or shock it. 
  • Bromamines: If chloramines are the unwanted byproduct of chlorine, then bromamines are the same relating to bromine. You can get rid of pesky bromamines in your pool by adding more bromine or shocking the water. 
  • Clarifier: Everyone prefers their swimming experience to involve clear, clean-looking water. If your pool water is cloudy and you have guests coming over soon, you can use a pool clarifier to make the water look clear again. Using a clarifier does not solve the root issue of cloudy water, which could be its hardness or the presence of unwanted particles. It only temporarily makes your pool's water look crystal clear again. 
  • Flocculant: Flocculant is a helpful pool product to have on hand. Pool water could be cloudy and dirty because of small particles, but these particles might be too small to filter out. Flocculant causes these particles to clump together, making them easier for you and your pool filter to skim out. 
  • Algaecide: The last thing you want to see is algae growing in your pool. Use an algaecide product to help get rid of algae and prevent it from showing up again. 

Factors That Can Disrupt Pool Chemistry

It would be great if you could balance your pool water's chemistry and forget about it for the rest of the season. The truth is, your pool is going to encounter many factors that will disrupt its chemistry and threaten its well-being. Here are some of these factors:

  • Regular use: When people use your pool, they do a lot to affect the water's chemistry without even realizing it. Sweat, bodily oils and hygiene products like soap and shampoo all affect the water's pH levels. 
  • Debris: The natural world is unpredictable and can take a toll on your pool chemistry. Sticks, leaves, grass and dirt will find their way into your pool water and impact the balance of your pool's water. 
  • Animals: Every once in a while, you may find a critter in your pool water or in the skimmer. From larger animals like rodents to smaller animals like insects, these creatures are better off far from your pool because their presence will disrupt your pool's chemistry. 
  • Rain: Rainwater has a pH of its own. After it rains, especially if the rainfall is heavy, your pool water's chemistry could become unbalanced. 

How to Check the Chemicals in a Pool

To get the chemistry in your pool right, you need to check the water's chemical levels regularly. One way you may be familiar with is to use a pool chemistry testing kit. These kits include water testing strips and other chemicals to give you readings on pool water samples — but this method can be tedious and feel like quite the chore after a while. 

There's a better way to check the chemicals in your pool — WaterGuru SENSE. WaterGuru SENSE makes pool care easier by monitoring the chemical state of your pool water at any given time. All you have to do is place it in your pool's skimmer and let it get to work. Then, using the accompanying smartphone app, you can connect to SENSE for real-time readings of your pool chemistry, whether you're lounging by the water or on a business trip across the country. 

Make Pool Care Hassle-Free With WaterGuru SENSE

Make Pool Care Hassle-Free With WaterGuru SENSE

If you're ready to take the next step toward enjoying the pool care process more, it's time to get WaterGuru SENSE. You'll see for yourself how pool maintenance can be so much easier all season long. You check your banking, email and other services right on your smartphone — why not your pool's chemistry, too?

Order WaterGuru SENSE today to experience a new way of caring for your pool. You'll wonder how you ever did it any other way.

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