A Note About Ideal Water Chemistry:
All of the chemical parameters listed below must be considered in relation to all the other parameters. All of these parameters work together as a system, none stand alone. For instance, to maintain good water balance indexes, low pH in pool water must be offset by a higher calcium hardness. High Total Alkalinity makes pH more difficult to change, but pH will rise a bit easier than it will go down when pool water has high TA levels. Chlorine is more effective (i.e. produces more HOCL and a higher ORP) at a lower pH, but the lower pH affects water balance. In a sense, there is really no "ideal" chemical level; there is only "ideal" results from a combination of the different parameters that produce safe, effectively sanitized pool water with a good ORP and non-damaging water balance.
Free Chlorine Range
Ideal Range = 2 ppm - 5 ppm
To increase: Add chlorine.
To decrease: Add sodium thiosulfate.
Ideal Range = 7.2 - 7.8
To increase: Add soda ash.
To decrease: Add muriatic acid, sodium bisulfate or CO2.
Range = 60 ppm - 150 ppm
Ideal Range = sodium hypochlorite pools: 80-120 ppm TA; Cal Hypo pools: 60-80ppm
To Increase: Add sodium bicarbonate or CO2
To Decrease: Column pour muriatic acid or add sodium biosulfate
Range = 150 ppm - 1000 ppm
Ideal Range = 500 - 800 ppm
To increase: Add calcium chloride.
To decrease: Dilute, dilute, dilute...
Cyanuric Acid/Chlorine Stabilizer
Range: 10 - 30 ppm
Ideal: 15 ppm
To Increase: Add granular cyanruic acid
To Decrease: Dilute, dilute, dilute...