Total Alkalinity refers to the amount of alkaline material (carbonates, bicarbonates and hydroxides) in your pool water. The proper range of TA is 120 to 175ppm. High TA can cause: eyes irritation, cloudy water, scaling and make pH difficult to adjust. Low TA can cause: eye burn, etched plaster, corrosion and staining.
pH is a measurement of relative acidity and basicity (alkalinity) of water. pH is measured on a scale that runs from 0 to 14. pH values below 7 are acidic and values higher than 7 are basic (alkaline). Your pool water should always have a pH in the range of 7.4 and 7.8.
Total Hardness refers to the amount of calcium and magnesium carbonate in the water. High CH can cause: cloudy water and scaling. Low CH can cause: etched plaster, corrosion and staining.
Sanitation refers to the control of infectious organisms (bacteria, virus, etc.), the removal of excess organics (perspiration, urine, body oils) and the preventtion of algae growth.
No matter which form of chlorine is used, you must maintain a chlorine residual of 1-3ppm. If the residual does not drop below 1ppm, the water will be sanitary.
To effectively eliminate chloramines from pool water, super chlorination or "shocking" is necessary. Shocking should be performed on a weekly basis or whenever you notice a "chlorine odour".
Algae are the microscopic forms of plant life that are introduced into your pool through rain, wind and dust storms. There are many types of algae, some of which are very resistant to regular chemical treatment. For this reason, algae can grow in pools even if the chlorine residual is in the proper range. It is easier to prevent algae than to kill an existing growth. In algae prone areas (usually, but not limited to hot humid climates with an abundance of plant life), the use of a good algaecide is recommended on a regular basis.