Proper water chemistry is required to keep a swimming pool safe and clean for swimmers, and maintaining a swimming pool’s chemicals can save pool owners time and money.

By following these steps, any pool owner can maintain their own swimming pool with the same results as the high-priced professionals.

Determine what type of chlorine you should use

Chlorine, which kills bacteria, algae, and microorganisms, is available in bottles, 3-inch tablets, 1-inch tablets, sticks, and a granular form; however, upon inspecting the labels, you will see that the active ingredient is exactly the same in all of them. Despite the wide range of prices, the only real difference you may find is the concentration of the active ingredients. The active ingredient in 3-inch tablets, 1-inch tablets, and sticks is called “Trichlor” (or Trichloro-S-Triazinetrione), and the active ingredient in granular chlorine is called “Dichlor” (or Sodium Dichloro-S-Triazinetrione).

The most common (and therefore the least expensive) form of chlorine is 3-inch tablets, which are slow-dissolving and require less maintenance. Chlorine sticks are larger and dissolve even slower than 3-inch tablets but are not as popular. 1-inch chlorine tablets dissolve more quickly than 3-inch tablets or chlorine sticks and are better suited to above-ground swimming pools, small in-ground swimming pools, and spas. Look for a concentration of 90% Trichloro-S-Triazinetrione in chlorine tablets or sticks.

Note that cheap, “big box” slow tabs and sticks tends to have binders and fillers that keep the tablet together. You will notice the difference as they dissolve: cheap tabs and sticks tend to crumble or fall apart within 2 to 3 days as opposed to gradually dissolving and maintaining their shape.

Granular chlorine works just as well as the tablets and sticks mentioned above; however, inorganic chlorine such as calcium hypochlorite must be pre-dissolved in a bucket of water before adding to a swimming pool. It must also be added to the swimming pool almost every day. Other types of organic chlorine (Sodium Dichloro) or inorganic Lithium Hypochlorite do not need pre-dissolving. These allow very precise control over the chlorine level of the swimming pool but require daily testing and addition of the chemical. Look for a concentration of 56% to 62% Sodium Dichloro-S-Triazinetrione in granular chlorine.

Use cyanuric acid with caution

Cyanuric acid (CYA, also called isocyanuric acid) is found in dichlor / trichlor tablets. Although cyanuric acid it is a stabilizing ingredient in chlorine that prevents it from being destroyed by the sun,[1] it does so at the cost of reducing the effectiveness (ORP, or oxidation reduction potential) of the chlorine. If you do use cyanuric acid, be sure to test the levels. If the levels are too high, the chlorine will completely lose its sanitizing ability.

Certain new studies are showing that CYA really needs to be maintained at a level no higher than 40 ppm allowing chlorine to perform optimally (high levels of CYA contribute to TDS or Total Dissolved Solids which “interfere” with chlorine activity).

If you choose to avoid cyanuric acid, look for calcium hypochlorite (solid) or sodium hypochlorite (liquid). You should also make an extra effort to test your pH; these two chemicals contain strong bases and will raise pH if used in sufficient quantity.

Add the chlorine to your swimming pool

Floating chlorine feeders and automatic chemical feeders, available from any pool supply distributor, slowly dissolve 1- and 3-inch chlorine tablets or chlorine sticks into your pool water. Automatic chlorine feeders are a great help to properly maintaining your swimming pool. Chemical feeders slowly meter out precise amounts of chlorine into your pool water automatically, and offer very precise control over the amount of chlorine being added to the swimming pool. If a feeder is adjusted properly, you may not have to worry about your chlorine level for a week or more.

You should never simply dump chlorine tablets or sticks into your swimming pool or place them in the skimmer basket of your swimming pool (though there are certain brands made that only dissolve when water is flowing over them). If a chlorine tablet is dissolving in your skimmer basket, all of the water passing through your pool plumbing and circulation system will carry a high level of chlorine. This high concentration of chlorine (which gives the water a very low pH) slowly eats at the inside of the circulation system and can cause premature failure of your pool pump and filter components.

Shock the pool weekly

As it works to clean your pool, chlorine binds to other chemicals like ammonia and nitrogen, which not only render it effectively inactive, but also create an irritant that can cause skin conditions like jock itch.[2] To eliminate combined chlorine, apply an occasional dose of shock treatment.

Follow up the next morning with a maintenance dose of algaecide. Algaecides are surfactants that work on pool surfaces to prevent algae from growing.

Maintain a proper pH level

This can be just as important as having chlorine in the pool at all. The pH level in your pool should be about the same as the pH level of human tears, 7.2, though in the range of 7.2 – 7.6 is optimal. Chlorine is about 10 times more effective at sanitizing your water when the pH is at 7.2 rather than at a high ph level of say 8.2. pH can best be measured with a drop-type test kit versus a test strip, which can be easily misread.

Most often you’ll find the pH level is high; the best way to lower pH is by slowly pouring “Muriatic Acid” (AKA Hydrochloric acid) directly into the deep end of the pool while the pool pump is on and the water is circulating. However, granular acid (pH Minus or Decreaser) is safer to use alternative than Muriatic Acid.

When adjusting pH, add smaller amounts then retest after about 6 hours of continuous filtration. Readjust as needed. This will prevent “bouncing”. If you have a true pH bounce problem, that is typically due to a LOW Total Alkalinity issue; once properly adjusted, the pH should maintain itself well over a period of 1 to 3 weeks depending on rain, use, etc.

If swimmers are having a problem with “burning eyes,” high or low pH is probably to blame, not high chlorine.

Test the water at least two times per week to ensure balance

Maintain your pool chlorine (FAC or free available chlorine – the good kind) level at 1-3 ppm at all times and you are guaranteed an easy and low-maintenance swimming season!