WATER CHEMISTRY

Water is water, isn’t it? If I can drink the water, why can’t I swim in it? These are good questions, but the answers may not be simple. As you remember from chemistry in school, all water starts as H20. But what happens after that is why all water is not the same. If the water comes from a well, there are usually minerals and metals dissolved in the water because of underground conditions. If the water comes from a municipal source, there may be chlorine, fluoride, phosphates, and other compounds added to the water.

Water that comes from you tap may be safe to drink, but it is probably not safe to swim in. When you fill the pool, the water probably has minimum levels of bacteria, germs, or algae present. However, exposing that water to the air, sunlight, and to swimmers, causes great changes to take place in the water. Thankfully, most changes are manageable so you can make it safe to swim.

WATER BALANCE

Water Balance is a term used to describe the condition of the pool water when all the factors such as pH, total alkalinity, calcium hardness, total dissolved solids, copper, iron, and manganese along with temperature of the water are in their proper relationship. Water Balance is measured by a formula called Langlier’s Index. The ideal index reading is 0. A significant plus reading will cause scaling and cloudy water. A significant minus reading will cause etching, wrinkles in liners, and “red eye” in swimmers.

pH

The term pH is a chemical symbol measuring the potential of hydrogen expressing the acid to base ratio of the water in the pool. The pH scale reads from 0 to14 with midpoint of 7 being neutral (neither acidic or caustic). What new owners have trouble remembering is that this scale is logarithmic and not numerical. This means when you move from the neutral 7 up to the reading of 8, you have not increased the amount of caustic in the water one time, but multiple times!

TOTAL ALKALINITY

Total alkalinity is the measurement of the carbonate, bicarbonate, and certain other alkaline (caustic) chemicals in the water. The desired range is between 80 and 150 ppm. A low total alkalinity reading increases the sensitivity of pH changes in the water. This will allow the pH to “bounce” up and down. This is not good for the pool or the equipment. If the total alkalinity is high, the water will be cloudy and will use a lot more of the sanitizer.

CALCIUM HARDNESS

Calcium Hardness is the measure of the combined calcium ions present in the pool water. The ideal range is 200 to 300 ppm. A low calcium hardness concentration will cause the water to be a pale clear green and in the case of a plastered pool the water will actually attack the plaster. A high calcium hardness concentration will cause cloudy water and a very high concentration will cause the water to be a milky white

STABILIZER

Stabilizer is a white powder called Cyanuric Acid. Stabilizer does not help in disinfecting or algae kill, but in the right concentration stabilizer greatly aids in reducing the chlorine demand of the water. Bright sunlight can draw the chlorine concentration out of a pool within a matter of a few hours. You could have the correct chlorine reading in the morning and a green pool in the afternoon if the correct amount of stabilizer is not in the water – 30 to 40 ppm range.

CHLORINE

Chlorine comes in all types, concentrations, and container sizes. The effective sanitizer is the hydrochlorous ion that is part of the molecule of the different chlorine sanitizers. Chlorine is a mix of organic or inorganic compounds and varies from a concentration of 5% such as NaOHCl2 (bleach) to 99% C3N3O3Cl3 (Trichloro-S-Triazinetrione). Not only does chlorine vary in “strength” but different chlorine compounds dissolve at different rates, have different pH values, and most importantly, have different uses. There is a section listing the different chemical formulas for sanitizers and their properties and uses later on in this booklet. Treat all chemicals with utmost care and follow the label instructions exactly! NEVER PUT ANY TYPE OF NON-STABILIZED OR POWDERED CHLORINE IN A FEEDER! IT MAY EXPLODE WHEN MIXED WITH WATER!

 

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