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Water chemistry and proper filtration is the key to clean and healthy water in your pool or spa. Regardless of the size of your pool or spa, the same chemicals are used and the same levels for balancing apply only the quantities vary. Pool water chemistry is the most misunderstood, yet vital component to overall pool and spa care. Not only does proper water chemistry protect the swimmers using the pool, but it also protects the swimming pool itself.

Gas heaters, electrical heat-pumps, filters, and even the vinyl-liner can all suffer severe damage from unbalanced pool water. Every pool, each season, creates its own demand for different chemicals. Everything that enters the body of water affects water balance: swimmers, rain, pollution, grass clippings, fertilizers, animals and chemicals. The neighbor’s pools, with exactly the same systems and environment may react totally differently from one another. Every pool also develops a chemical usage pattern each season. After observing how each pool reacts to different bather levels, rain and the environment, you will get a handle on your pools’ chemistry patterns and what’s required to keep the water balanced.

Water balance is the relationship of various chemical parameters to one another within your swimming pool or spa water. A pool that has "balanced" water has proper levels of pH, Total Alkalinity, chlorine and Calcium Hardness. It may also be defined as water that is neither corrosive nor creates scaling. The constant shifts and changes in the chemical balance of your pool water can be impacted naturally by the sun, wind, debris and rain. The water balance can also be impacted by skin oil, dirt, cosmetics and other compounds that humans introduce to pool or spa water while swimming. What can you do to keep the pool water in balance? Start with a high-quality water testing kit (with fresh testing re-agents) to measure the chemical parameters of pH, alkalinity, chlorine and calcium hardness.

Keeping your pool water clean, clear and healthy depends on the following factors, all of which work together to give you sparkling clear water, and a swimming pool that's enticing, healthy and comfortable to use:

Water balance - chemicals used in swimming pools typically include:

Disinfectants: to destroy harmful or otherwise objectionable organisms or bacteria (the most commonly used by residential pool owners is Chlorine)

Alkalinity and pH Adjuster: to maintain a consistent acid-base relationship and acid buffering capacity.

Algaecide: to kill and prevent algae

Filter Aids: to help remove foreign material

Good maintenance (brushing above and below the water line/vacuuming)

Proper Filtration and regular backwashing

Phosphates additives: maintaining proper levels will insure that chemicals react the same each time they are applied to your pool and spa

NOTE: It's always important to read and follow and manufacturers' instructions regarding the use and storage of swimming pool chemicals.

The following is a list of general pool and spa chemical parameters for keeping your swimming pool water well-balanced and safe. Based on your type of pool and the region of the country you live in, the recommended ranges may differ slightly. Sanitizer levels (and sometimes water balance parameters) can also vary depending on the specific sanitizing program you are using.

A balance of water chemistry factors will provide friendly water that will not damage pool components and is non-irritating to swimmers. It is then necessary to provide for disinfection of the water to prevent the spread of disease organisms from person to person and prevent unwanted growth of bacteria and algae in the pool.

Accepted levels for balanced pool or spa water

  Pool Spa
 Total Alkalinity  
  Plaster 80-120 ppm 80-120 ppm
  Vinyl 100-150 ppm 100-150 ppm
 pH 7.2-7.6 7.2-7.6
 Bromine 2-4 ppm 2-4 ppm
  Total 1-3 ppm 2-4 ppm
  Free 1-3 ppm 2-4 ppm
 Cyanuric Acid 30-50 ppm 30-50 ppm
 Calcium Hardness  
  Plaster 200-400 ppm 200-400 ppm
  Vinyl 175-300 ppm 175-300 ppm
 TDS <2000 <2000
 Heavy Metals: Copper, Iron, etc<0.3 <0.3