Water Chemistry


Pool Water chemistry is important to proper pool maintenance. Here are the different elements of water chemistry (unless noted otherwise, check two to three times a week):

pH Level

  • Keep between 7.4 and 7.6
  • Below 7 –
    • water is too acidic
    • corrodes walls and irritates skin
    • use pH increaser
  • Above 7.6 –
    • water is too basic
    • causes cloudy water, deposits on walls and dries the skin
    • use pH decreaser

Alkalinity Level

  • Keep between 100 to 150 ppm (parts per million)
  • Stabilizes pH levels
  • Use alkalinity increaser when too low

pH and Alkalinity Levels

  • If both are low, use alkalinity increaser first to increase both levels; then add pH increaser, if needed
  • If both are high, use pH decreaser to lower both levels

Calcium Level

  • Keep between 180 and 220 ppm
  • Used with plaster pools
  • Too much causes white hard water stains; too little causes corrosion
  • Used at beginning of swimming season and checked monthly thereafter
  • Too low, use calcium hardness; too high, drain water level some and refill with fresh water

Chlorine and Alternatives

  • Kills bacteria and algae
  • Chlorine –
    • keep between 1 and 3 ppm (3 is recommended)
    • use stabilized chlorine with active ingredient of either Trichloro or Dichloro to slow down sun burn off
  • Bromine –
    • keep between 3 to 5 ppm
    • used for indoor pools and hot tubs; not for outdoor use in sun
    • not as effective in dealing with algae
  • Biguanide
    • keep between 30 and 50 ppm
    • must purchase special brands of other water chemicals
  • Minerals
    • keep at 0.5 ppm
    • still requires the use of some chlorine
  • Pool Shock
    • done weekly – more during hot weather
    • burns off unwanted chlorine residue
    • more effective to do after sun is down
    • no swimming for 24 hours
    • always read chlorine or alternative label for instructions

Water Stablizer

  • Follow directions on container
  • Protects chlorine or alternatives from sun burn off
  • Used when you first fill the pool with fresh water


  • Chlorine kills algae best; use algaecide as a backup
  • If major algae problem, call a professional for pool maintenance service

Water Clarifier or Floc

  • Water clarifier brings together the tiny particles that make the water cloudy and removed by the pool filter
  • Floc (Flocculant) also brings them together but then pool must be vacuumed to remove

If you have Questions about Water Chemistry please contact our Lab at ext. 130


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