The essential ‘three Ps’ of pool care

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Since 1990, HydroTher Hot Tubs have been the #1 choice of architects, consultants, designers and facility operators for commercial aquatic applications.

There are many chemicals involved in creating a clean and safe pool, and they can be broken down into four main categories: sanitizers, oxidizers, algaecides, and ancillary chemicals. Each plays a different role in the “Three Ps” of pool care:

These chemicals work together to create a successful pool care routine. Categories, such as sanitizers, oxidizers, and algaecides are “non-negotiable.” These are required for pool maintenance, regardless of the form they take. Other categories, such as ancillary chemicals, are “negotiable.” These products may not be required, but they play an important part in the quality of the pool water and bring value to consumers by saving time, money, and providing a better swimming experience. Ultimately, all four categories, along with proper circulation and filtration, work together to make pool care as easy and effective as possible.


The main job of a sanitizer is to kill bacteria and prevent diseases. The most crucial step in pool care is maintaining a sanitizer residual in the pool. Constant sanitization is key for preventing diseases. There are different forms of products available for pools, including sticks, tabs, liquids, and granule products. They are all applied differently, but ultimately do the same thing: kill bacteria. However, each type has a different impact on the water, and this is something pool technicians need to consider. For example, liquid chlorine is an effective sanitizer and is easy to apply, but it drives the pH of the pool water up when used routinely. Trichlor tablets can be applied in a variety of ways but cannot be added directly to the pool itself. However, the level of chlorine provided tends to be stable and it is easier to maintain a steady residual than it is with liquid chlorine. Using salt as the sanitizer reduces maintenance and provides a steady chlorine residual, but the equipment required can be expensive and will need to be replaced periodically. However, all these options are effective for sanitation.



Oxidizers, also known as shock products, are used to complement sanitizers. Shocking a pool breaks down and removes a wide variety of contaminants in the water. Elevating the sanitizer levels can also break down contaminants, but those chemicals tend to deplete very quickly in the process. The addition of
a shock product helps reduce the amount of work the sanitizer must accomplish to keep the pool clean and clear. Shocking will help make it easier to maintain the constant sanitizer residual needed by breaking down bather waste and other contaminants; leaving the sanitizer to do its main job of killing bacteria. The shock product can be thought of like a broom and the sanitizer is as a mop. The mop does the heavy-duty work of cleaning a floor, but the job is much easier with a quick sweep using a broom first. The combination of sanitizing and shocking is what makes the water safe.

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Algaecides specifically prevent or kill algae. A good product will eliminate and stop the growth of green, black, and mustard algae, which are the most common types found in pools. There are many different types of algaecides including chlorine (Cl), bromine (Br), copper-based products, and quat-based products. Copper and quat-based algaecides are very effective at working with chlorine or bromine to kill algae without relying on the sanitizer to do the work.

The fastest and most efficient products are a combination of technologies which will do both, kill and prevent algae growth in many ways. A pool technician could also deploy sanitizers to control algae, however, they are slower and less effective. Algaecide provides an extra layer of protection against algae growth and reduces the strain on the pool’s chlorine residual. Quality algaecides will create a residual in the pool, providing protection without needing to add products every day.

Ancillary products and balancers

The last category of pool chemicals can be generalized as ancillary products. While the three categories above are non-negotiable pool care products, ancillary products are not outright required for pool water maintenance. However, they still add value and efficiency to pool care programs. These products include enzymes to help remove non-living contaminants, scale prevention, and metal control products to protect the pool surfaces and equipment. They also include clarifiers and phosphate removers to help improve water quality and clarity. Ancillary products can save the end-user’s time, money, and can help provide better water with minimal effort.

One subset of ancillary products is the “balancer” category. Balancers are exactly what they sound like: products to balance the chemistry of the pool. Its parameters include pH and total alkalinity (TA) to control the acid/base balance of the water, along with calcium hardness adjusters to keep water from being aggressive or scale-forming. Balancing the water leads to a comfortable environment for swimmers, clear water, and functional pool equipment over time.

A deeper look at sanitizers

Sanitizers are the main product people think about for pools, and there are many different choices available. Trichloroisocyanuric acid (TCCA) is the most common type of sanitizer. Most commercially available sanitizer sticks and tabs are made of TCCA, as they offer an ease-of-use benefit for consumers. This is mostly due to the slow dissolving nature of the product. Trichlor sticks or tabs can be used in feeders, floaters, or introduced through the pool skimmer to provide a continuous source of chlorine sanitizer to the pool as the product dissolves. Since trichlor dissolves over a span of days, users can add the product and let it be, knowing a refill is not likely necessary for several days.

Calcium hypochlorite (Ca[OCl]₂) and liquid chlorine are also commonly used chlorine sanitizers. Ultimately, these products do the same thing as trichlor: they kill bacteria and prevent disease. However, the process of applying and maintaining these chemicals is different. Calcium hypochlorite and liquid chlorine both disperse immediately when added to the pool water, rather than slowly dissolving over time. This puts a large amount of chlorine into the pool at once, which is sufficient until the next dose.

For example, if a user adds calcium hypochlorite to the pool and 10 kids go swimming the next day, there is a good chance all the chlorine would be gone when they are done. If trichlor was being fed into the pool, the chlorine residual would be supplemented throughout the day and probably still be measurable after the pool party. In the case of calcium hypochlorite and liquid chlorine, it would need to be added again within a day or two to maintain the residual. This is clearly more work for the pool owner. If a service company were taking care of the pool, it would not receive more chlorine until the technician returned to add it, leaving the pool at risk.

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In addition, trichlor already has cyanuric acid (CYA) blended into it. CYA is sunscreen for the sanitizer. Without it, the ultraviolet (UV) rays of the sun burn up chlorine very quickly. With CYA, it lasts 13 times longer in the sunlight. Using trichlor as the sanitizer of choice allows users to add product less often, feed continuously, and lose less chlorine to waste—making it an extremely efficient form of chlorine. Calcium hypochlorite and liquid chlorine do not contain CYA; however, it can be added separately, but that adds an extra step required to protect the chlorine residual.

Sanitizer choice also impacts water balance. While trichlor has a low pH, both calcium hypochlorite and liquid chlorine have high pH. The slow feed of trichlor minimizes the impact of a low pH in a pool, but the “all at once” addition of calcium hypochlorite or liquid chlorine often cause the pH to rise dramatically, leading to cloudy water and scale issues. Further, frequent use of calcium hypochlorite adds calcium to the pool overtime, and eventually, calcium levels will get too high, leading to problems with scaling, and surface damage. As a result, a scale inhibitor product will be needed to keep the water clear.

Ultimately, there are many choices to pool care. Some categories, such as sanitizers, are non-negotiable and an integral part of every pool care program. Other categories, such as ancillary products, are not necessary, but can lead to an easier and more efficient pool maintenance routine. Establishing key products and determining what works best for each pool is the key to successful water quality management. The result is clear, safe, hygienic water and happy swimmers.

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