Pool water chemistry basics
- Published on Tuesday, 14 February 2012 00:21
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Pool water chemistry is something that baffles many homeowners caring for their backyard pools. It is vital to keep an adequate level of certain chemicals to create pristine, safe swimming water.
One of the most important tools to have is a pool/spa test kit. Sometimes pool packages will come with a basic test kit that measures for chlorine and pH only. This isn't really adequate for most people's needs.
Understanding the different facets of pool water chemistry will help illustrate why.
There are roughly six factors that come into play with pool water chemistry.
1. Free chlorine (FC): Swimmer protection is provided by a sanitizer, generally a chlorine-based product. Free chlorine residual is the measure of the active, available chlorine sanitizer in the pool that is still able to clean the pool. Without FC, the pool will harbor bacteria and algae and turn swampy.
2. Combined chlorine (CC): When chlorine combines with contaminants in the pool, like ammonia and organic materials, it essentially gets used up and becomes inactive. This is called combined chlorine. This type of chlorine is useless at this point and can contribute to that chlorine smell many people associate with too much chlorine in the pool. Rather, the opposite is the case. There is too much used-up chlorine and not enough FC. If CCis too high, it will be necessary to superchlorinate, or "shock" the pool, to rid the water of CC.
3. Total chlorine (TC): This is the measure of the FCand CC in a pool. In perfect conditions where CC is zero, TC tests can be used in place of FC tests. However, most home pools have occasional issues of algae blooms or other problems, rendering a TC test inadequate for measuring true chlorine levels.
4. Cyanuric Acid (CYA): Cyanuric acid is a product that helps buffer chlorine from the effects of the sun. Essentially you can think of CYAas sunscreen for chlorine. Without CYA, also known as stabilizer, in pool water -- and the right level of it present -- chlorine will burn off very quickly in the water. In full sunlight, it's possible for chlorine to evaporate as fast as it is put into the pool without CYA.
5. pH: This is the measure of whether the water is acidic or alkaline. Generally for swimming comfort, the pH of the pool should be kept between 7.2 and 7.6. This way there is no erosion of metal parts or discoloration of pool walls from water that is improperly balanced. Other chemicals in the pool also work more in harmony when water pH is right.
6. Total Alkalinity (TA): TA helps buffer the pool water against big swings in pH levels, making the pool water more consistent. SH122815
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