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Swimming Pool Chemistry 101

As a pool owner, it is important to understand the two basics of swimming pool chemistry: sanitation and the balance of water.

Pool Chemistry Oxidation


In order to keep a clean and sanitary pool that is safe to swim in, you will need to utilize some form of pool sanitizer. Some of the common choices available include Bromine, Chlorine, Minerals and Biguanide.


If you are searching for an alternative to chlorine to avoid the odor, then bromine is certainly an option. Although this chemical is more commonly used in hot tubs and pools that are indoors, it can be used in outdoor pools that are not in direct sunlight. However, it is important to recognize that it might not be strong enough to combat some types of algae and that sunlight can cause it to make water unstabilized. Bromine levels should be maintained between 3 to 5 ppm for proper sanitation.


The classic choice for pool sanitation, this chemical is a great algae and bacteria killer, not to mention it is rather cost-effective. When shopping for chlorine, you want to purchase Trichloro or Dichloro forms as they do not become unstable underneath the sunlight as quickly as chlorine that doesn’t include them as an active ingredient. Chlorine tablets can be purchased and implemented in three different forms: powdered chlorine, chlorine tablets and through salt chlorine generators. The proper Chlorine levels to maintain in a pool are between 1 to 3 ppm.


Some pool owners choose to use minerals as a replacement for a portion of the chlorine that is required to sanitize their pool (because minerals alone do not sanitize properly). Copper and silver minerals can be used by installing an ionizer which releases them slowly into the water. If you are using minerals in your pool, chlorine levels should still be about .5 ppm.


Biguanide is another option which can be used instead of chlorine in a pool. Two common types of Biguanide are SoftSwim and Baquacil, both of which should not be intermixed with any other type of pool chemical product. Keeping Biguanide levels between 30 to 50 ppm is proper for a pool, and can even make the water of your pool feel somewhat smoother. In addition to using these chemicals on a regular basis to sanitize your pool, there are going to be times when you might have to shock your pool. Called oxidation, this procedure is needed when particles begin to float in the water when chlorine kills bacteria in the pool, this is known as a chloramine. Shocking your pool helps to break up these chloramines, this is done through the addition of chlorine to reach the breakpoint oxidation. Typically this breakpoint oxidation can be reached when the levels of chlorine in your pool are 10 ppmabove their normal reading.

Water Balance

The balance of your pool water is a rather important, yet intricate, process that requires a basic knowledge of a little bit of chemistry. The three ways to help ensure that your pool is properly balanced is through calcium hardness, alkalinity and pH levels.

Calcium hardness

The proper balance of calcium is meant to help protect your pool. When there is too little calcium in your pool you’re the water can begin to eat away at the plaster of the pool, but too much calcium can cause scaling. Adding calcium hardness might be necessary to keep the levels ideal in your pool, which is 175 to 225 ppm in non-plaster pools (200 to 275 ppm in plaster pools).

pH levels

First, you will have to maintain the proper pH level of pool water, which is just above neutral on the pH scale, between 7.4 and 7.6. pH levels are measured on a scale from 1 to 14, with 7 being neutral. Those liquids that measure below 7 are considered to be acidic, and potentially dangerous the lower the number, and as pH increases to 14 liquids become more basic. Your pool water can certainly be altered by anything it is exposed to, including swimmers and rainwater. Not having your water between the appropriate pH levels can cause an imbalance in your pool water.


The alkalinity of your pool water is directly related to the pH of your water, it is meant to help absorb some of the changes that can cause dramatic shifts in the pH of your pool water. The proper alkalinity of your pool water is between 100 to 150 ppm. The best way to ensure that your pool water is balanced is by monitoring the alkalinity and pH levels of your water. It is recommended that once a week you use test strips to test both levels. You want to have three common chemicals on-hand at all times:

  • Alkalinity increaser

  • pH reducer

  • pH increaser

When you properly use these chemicals and complete your weekly testing, you will actually notice that your sanitation efforts are much more effective.

Other Chemicals You May Need to Know About

Sometimes, no matter how much chlorine is in your pool and how balanced your water may be, there is a need to incorporate other chemicals into your pool water.


While chlorine should be your number one option to killing algae in your pool, sometimes you can take preventative measures and use algaecide to keep algae at bay until your chlorine levels can be increased to their appropriate levels again.

Water Stabilizer (Cyanuric Acid)

Consider Cyanuric Acid as a chlorine protector when you are adding chlorine to your fresh water. This chemical helps chlorine from burning off quickly in the sunlight.

Scale and Stain Remover

Stain and scale remover, often called metal remover, is used to help filter out the metals like iron and copper from your pool. By taking out these metals you can help to reduce the unsightly stains that they cause throughout your pool.

Floc and Clarifier

Water clarifier is used to help the minute particles causing the cloudiness of your pool together so that they can be removed easier with the filter. Floc works in a similar fashion, though it makes larger particles out of those minute ones and sinks them to the bottom of your pool so that they can be vacuumed out. Keep in mind that through a clear understanding of pool tools and chemistry you can maintain a healthy, fun and clean environment to swim in.

Chemicals, circulation and cleaning should be the important C’s that you always keep in mind when taking care of your pool.

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