A swimming pool provides a source of fun, relaxation and exercise for family and friends and, if municipally or club-owned, for the general public. However, pool water that has a high level of calcium and magnesium could cause discomfort to swimmers and damage to pools or plumbing systems and may require water-softening treatments to correct the problems associated with hard water.
Water is considered to be either hard or soft. Hard water results when an excess amount (over 1 grain per gallon, or gpg) of minerals such as calcium and magnesium dissolve into groundwater, which is water from rain, snow and underground rivers. Soft water usually comes from above-ground sources like rivers and lakes and contains little minerals.
According to Allan Schuster, a pool expert, the level of calcium hardness or total hardness of magnesium and calcium in pool water should be between 150 and 200 parts per million (ppm). Levels below that require adding calcium to the water to reach an equilibrium, thus avoiding problems like dissolving or etching of the pool walls. Levels above 200 ppm increase calcium deposits. Proper balance means maintaining a pH level of 7.2 to 7.6, total alkalinity between 80 and 120 ppm, and a total hardness level of 150 to 200 ppm. Vinyl pools should have a calcium hardness of 80 to 150 ppm, and pools with a masonry finish should have levels between 150 and 200 ppm.
Effects of Hard Water
The excess amount of calcium and magnesium in hard water forms scales and buildup in pipes, causes decreased water flow, and eventually blocks the pipes. The mineral buildup could also cause water spotting and filming, and scratches on swimming pool tiles. It also causes swimmers to experience dry skin, eye irritation and hair tangles.
According to Rich Bruni, a water technician for Budget Water, a Pittsburgh, Pennsylvania, based company, before making a decision to use a pool water softener, first evaluate the pool water. Municipal customers rely on the municipality for information on their water quality and should contact the water superintendent or City Hall for testing. Customers who use private companies have the responsibility of knowing their water quality and should contact the county extension agent, a water conditioning company, or send samples to the state health department.
Resin-Ion Exchange and Zeolite-Ion Exchange Softening Treatments
According to Budget Water, to replace hard water with soft water, replace magnesium and calcium ions with sodium ions by running the hard water in a tank through a bed of small plastic beads, or through the chemical matrix zeolite, covered with sodium ions. However, this process will need to be regenerated or the tank should be flushed with sodium chloride periodically as the water returns the beads with magnesium and calcium over time.
Water balancers also help to maintain the correct level of calcium hardness but salt-based softeners should be avoided to prevent corrosion, scale buildup and clogging of pipes, according to Pool Time. Eco-friendly alternatives are household electronic hard water conditioners like the Hardmaster and the Small Wonder, which require no installation or maintenance and effectively change hard water molecules to soft crystals.
Schuster recommends using chelating or sequestering agents to prevent the pool walls from scaling or the water from becoming cloudy, or by adding a softener to the auto-fill line. Because treatment could be difficult or costly, pumping out hard water and replacing it with soft water is a good alternative. Another good choice, he says, is to use a pool magnetizer, a magnetic water conditioner (permanent magnets) which could be strapped to the return line of the pool and requires no power. This treatment eliminates the need to use sanitizers which increase calcium.The water changes when it is exposed to positive electric ionic charges in the magnetic field line, improving the quality of the water.