Two basic methods contribute to clean, clear swimming pool water: Filtration and chemicals.
Pool filtration removes the bulk of objectionable material from pool water. Chemicals1 clean and polish the water, removing organic material, killing micro-organisms, sanitizing, and maintaining the proper pH balance. The most common pool chemicals are chlorine or bromines, soda ash, baking soda, or caustic soda, sodium bisulfate or muriatic acid, algaecides, and flocculants/coagulants for clumping small particles of waste and debris together so they can be removed by vacuum or filtration.
- Chlorine comes in a variety of forms, e.g., gas, tablets, powders, and each form is added to the pool water in its own way.
- Chemical feeders are the best method of adding chlorine to the pool. A dosing pump on top of the feeder tank injects a premeasured amount of chlorine into the pump discharge line. Chlorine is pushed into the pool each time the pump runs.
- Chlorine tablets are placed in the pool skimmer basket where they dissolve into the water. Chlorine tablets introduce a high chlorine level at and around the pool skimmer and they take time to dissipate throughout the pool water.
- Bromines are added in the same fashion as chlorine.
Raising the pH level
- Add soda ash, baking soda, or caustic soda to the pool water at the skimmer to raise the pH to alkaline levels. Optimum pH levels are 7.2 to 7.8. Too high a pH level causes scaling and cloudy water. It can also negatively effect the way the chlorine works.
Lowering the pH level
- Add muriatic acid or sodium bisulfate to the water to lower the pH level.
- If the pH level is too low, it can cause corrosion of the pool mechanical components, etching of the pool walls and floor, and skin and eye irritation.
- Add the pH adjusting chemicals at the deep end of the pool.
Treating with algaecides
- Follow the algaecide manufacturer’s instructions for adding the chemical.
- Mineral sanitizers work well for adding algaecides to the pool water.
Pool maintenance with chemicals is a complicated subject. Each chemical added to the pool can change the chemical make-up of the pool water. Algaecides can affect the chlorine levels and efficacy and the pH levels. PH adjusting chemicals can alter the efficiency of chlorine or bromine.
Specific recommended amounts of each chemical should be added at regular scheduled maintenance periods after proper testing indicates the need for them.
Chemical additive requirements can also change depending on whether the pool is an indoor or outdoor pool and based on its size and depth.
Consult a pool professional for the proper chemicals to use on your pool, the proper amounts, and the proper mechanical or manual methods of introduction.
Reference1: Tom Harris:howstuffworks.com
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