How to Properly Maintain Swimming Pool Water Chemistry

How to Properly Maintain Swimming Pool Water Chemistry

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Properly maintaining pool water chemistry is perhaps the most important aspect of maintaining a swimming pool. Proper water chemistry is required to keep a swimming pool safe and clean for swimmers. Maintaining a swimming pool’s chemicals can save pool owners hundreds of dollars per year, and endless hours of time. Armed with a basic understanding of swimming pool chemistry, and by following a few simple steps, any pool owner can maintain their own swimming pool with the same results as the high priced professionals.


  1. Sanitize your swimming pool with chemical chlorine(cl), which is dissolved into your swimming pool water and combines with bacteria and other organics in the water on a molecular level to kill these harmful contaminants. Once chlorine combines with the bacteria and organics in the swimming pool water, the chlorine becomes inactive and no longer works to sanitize your pool. The combined chlorine and organic contaminants are burned off by a weekly shock treatment, and removed from the water by the pool filter system and then some.
  2. Determine what type of chlorine you should use. There seem to be many types of chlorine on the market, and each pool supply company works hard to make their chlorine product seem new and different. Chlorine is available in 3″ tablets, 1″ tablets, sticks and in a granular form. Upon inspecting the labels and comparing of all of the different brands of chlorine, you will see that the active ingredient is exactly the same in all of them; however, cheap & “big box” slow tabs & sticks tends to have binders & fillers that keep the tablet together (you will notice the difference as they dissolve – “cheap” tabs & sticks tend to crumble or fall apart within 2 – 3 days as opposed to gradually dissolving & maintaining their shape). The active ingredient in 3″ tablets, 1″ 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). You will find a very wide range of prices for chlorine, and the only real difference you may find between the many brands of chlorine is the concentration of the active ingredients. You should look for a concentration of 56% to 62% Sodium Dichloro-S-Triazinetrione in granular chlorine, and a concentration of 90% Trichloro-S-Triazinetrione in chlorine tablets or sticks. Granular Chlorine can also be in the form of Calcium Hypochlorite. It is typically only available up to 65%. For more information on different types of chlorine, see the tips below.
  3. Add the chlorine to your swimming pool. Floating chlorine feeders and automatic chemical feeders are available from any pool supply distributor, to automatically dissolve 1 inch chlorine tablets, 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. You should never simply dump chlorine tablets or chlorine sticks into your swimming pool, or place chlorine tablets or chlorine sticks in the skimmer basket of your swimming pool – although 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 carries a high level of chlorine. This high concentration of chlorine (actually the very low pH of the treated water – slow dissolving tablets & sticks have a pH of about 3.0) slowly eats at the inside of the circulation system, and causes premature failure of your pool pump and pool filter components.
  4. Although cyanuric acid (isocyanuric acid)stabilizes the chlorine level, it does it at the cost of reducing the effectiveness (ORP-Oxidation Reduction Potential) of the chlorine. Cyanuric acid (CYA) is found in dichlor / trichlor tablets. If you choose to avoid cyanuric acid, look for Calcium hypochlorite (solid) or Sodium hypochlorite (liquid). You should test your pH, these two chemicals contain strong bases and will raise pH if used in sufficient quantity. If you do use Cyanuric acid, be sure to test the levels. If the levels are too, high the chlorine will completely lose it’s 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).
  5. Maintaining a proper pH level 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. A pH level 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. Granular acid or pH Minus or Decreaser is “safer” to use alternative than Muriatic Acid.
  6. When adjusting pH, either increasing or decreasing, 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.[1]
  7. Also if you’re having a problem with “burning eyes” while swimming in the pool, high or low pH is probably to blame, not high chlorine (Free Available Chlorine – FAC – as distinguished from Total or Combined Chlorine). High Combined Chlorine (chlorine combined with swimmer waste and/or nitrogen, commonly referred to as chloramines [2]) also contributes to “red eye” necessitating a proper shocking of the pool to break up the chloramines.
  8. Or, consider using bromine instead. The chemical bromine is very similar to pool chlorine in the way that bromine kills bacteria and harmful contaminants, but the two pool chemicals react in different ways. Bromine is most commonly used to sanitize spas/hot tubs because it is more stable than chlorine in the warmer spa water temperatures, and because of the lack of chemical odor in the water. The chemical bromine is preferred by many pool and spa owners because it causes less irritation of the skin and eyes. Because bromine is so stable, it can be harder to wash the chemical smell from your skin after bathing in a pool or spa that uses bromine. Bromine is available in tablet form and can be added to pool water using a chemical feeder to dissolve the tablets. Special note: Bromine CANNOT be stabilized with Cyanuric Acid – don’t even try. For more information on deciding between chlorine and bromine see the tips below.


bromine is not an acceptable alternative to chlorine for a full size pool. alternatives may be a salt water system or a non-chlorine system such as baquacil.the active ingredient is biguanide. though it may be harder or more expensive, it is the best alternative to chlorine or salt because even salt water pool systems need some chlorine. if you use baquacil brand sanitizers you can still use any brand for the calcium or ph balance. one thing you would not put in your pool while using baquacil is (cya) cyanuric acid. find a dealer and know thata pool is a hobby; a hobby just like a fish tank with life in it.


  • A very common question for new pool owners is, “Which type of chlorine should I use?” The type of chlorine you select depends upon your application, your preferences or your pool maintenance habits. The most common (and therefore the least expensive) form of chlorine is 3” tablets. 3” tablets are slow dissolving, which requires less maintenance. You can fill a floating chlorine feeder or automatic chlorine feeder with large amounts of slow dissolving 3” chlorine tablets, and if the feeder is adjusted properly, you may not have to worry about your chlorine level for a week or more. Water testing should always be performed at least two times per week to ensure proper water balance. Professional testing should be done 3 – 5 times each season; professional testing will and should perform further tests usually not available to consumers: total chlorine versus free chlorine, cyanuric acid, acid demand, alkali demand, adjusted total alkalinity, calcium hardness, water temperature (makes a difference in overall water balance), total dissolved solids (TDS), iron, copper, QAC (quaternary ammonium compounds) or algicide level.
  • Chlorine sticks are larger and dissolve even slower than 3” chlorine tablets, but are not as popular. 1” chlorine tablets dissolve more quickly than 3 inch chlorine tablets or chlorine sticks, and are better suited to above ground swimming pools, smaller in ground swimming pools or spas. Granular chlorine works just as well as the tablets and sticks mentioned above, however granular chlorine (inorganic chlorine such as calcium hypochlorite) must be pre-dissolved in a bucket of water before adding to a swimming pool. Granular chlorine must be pre-dissolved and added to the swimming pool water almost every day. Other types of organic chlorine (Sodium Dichloro) or inorganic Lithium Hypochlorite do not need pre-dissolving. This allows very precise control over the chlorine level of the swimming pool, but requires daily testing and addition of the chemical.
  • The difference between chlorine and bromine is that once chlorine combines with bacteria or harmful organics to kill them, most of the chlorine is used up and will no longer work to sanitize your swimming pool. This “combined chlorine” will be burned off by the next shock treatment and removed from the pool water by the filter. When bromine combines with bacteria in pool water, the bromine is still active but combined with the bacteria and organic matter to neutralize these harmful contaminants. When you shock a bromine pool the shock treatment only burns off the harmful contaminants, and leaves a good portion of the bromine behind in the pool water. The bromine left behind is available to sanitize the pool again. The result is that the volume of bromine tablets needed to sanitize a swimming pool is noticeably less than the volume of chlorine needed to do the same job.
  • If chloramine or combined chlorine is allowed to accumulate, they will become more difficult to break-up or control leading to “smelly” water, cloudy water, irritated eyes & skin, early algae growth, etc. and becomes a chlorine demand [3]. When a chlorine demand is present, it will be difficult to maintain a secure chlorine level and requires a HUGE amount of chlorine to satisfy the demand (amounts of 50 or more pounds in 20,000 gallons of pool water is not uncommon). If the chlorine demand is NOT satisfied, the problem will only worsen as more chlorine is combined to form more & more chloramines. Special Note: much of the public (potable) water is currently treated using chloramines (chloraminization) thereby adding to the problem.
  • Shock the pool weekly to prevent and eliminate chloramines. Follow up the next morning with a maintenance dose of a good quality algaecide to prevent algae growth [4] (algaecides are surfactants so they work on pool surfaces where algae tends to grow.
  • There are definite advantages and disadvantages to using bromine in a swimming pool. Bromine is considered better by some pool owners because bromine is usually much less irritating to the skin and eyes. Many pool owners with naturally sensitive skin prefer bromine, however bromine is in the same periodic group as chlorine, and it may not help people who are allergic to chlorine. The disadvantage to bromine is that the chemical costs a good deal more per pound than chlorine.
  • 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!
  • Salt chlorinators are a great option for eliminating the need to handle chlorine or bromine (Do not attempt to convert a bromine pool to chlorine, even salt-chlorine. It is not possible. The chlorine generated will simply regenerate the bromine. [5]) A low level of salt is added to the pool instead and these devices automatically convert the salt to chlorine and maintain the sanitizing of the pool. Just be sure to watch your pH level as the chemical reaction that takes place here raises the pH level and will need to be lowered with “Muratic Acid”. Improper installation of salt/chlorine generators can lead to other pool problems [6] such as etching of pool surfaces, premature corrosion of metal pool parts & accessories even stainless steel, etc.


  • These chemicals are hazardous. Keep out of reach of children!
  • Make sure when using granular chlorine, you pre-dissolve it in a bucket of water before adding it to the pool.
  • Add chlorine to water and not water to chlorine as it may cause an explosion.
  • Muratic Acid is the best choice for lowering pH levels, but creates dangerous fumes and should be used with extreme care. Sodium bisulfate, granular pH minus or pH decreaser, is a “safer”, more homeowner friendly alternative.
  • Always follow product label instructions from the manufacturer.

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