Getting the Stains Out

Getting the Stains Out


Posted By on Dec 17, 2013

Getting the Stains Out of a pools surface sure makes things look at lot better.  All pool water contains metals. Some sources of dissolved metals are familiar: fill water, pool chemicals, deteriorating pool equipment, lawn fertilizers and other chemicals in rain runoff. More recently, the increased use of stone, brick and marble in and around pools has added to the levels of dissolved metals in pool water. This is because of the acidic nature of rainwater, which typically has a pH of 5.0 to 5.6, but sometimes as low as 1.8 in highly populated areas. Acidic rainwater releases the metals found in these materials. Marble, flagstone and granite, for example, naturally contain iron which can leach into a pool. Balanced pool water is essential. Poor chemistry in any pool, regardless of the water source, can eventually destroy pool equipment and surfaces. By its chemical nature, pure water is very corrosive. This point is especially important for owners of plaster pools to understand because if the water does not contain enough carbonate (alkalinity) or calcium (hardness), it can impact the plaster. Nor are vinyl pools immune: Severely unbalanced pool water can leach the plasticizer (the chemical added to vinyl to give it flexibility and elasticity) out of vinyl liners. pH is the most significant factor in preventing and removing stains, and is often overlooked because pool water can look clear even at very high or very low pH levels. Pool water with a low pH can dissolve the metals found in pool equipment and heat exchangers. And just as the stone and brick used around the pool can dissolve in acidic water, so too will the pool’s plaster surface, resulting in more surface pitting and etching and the release of embedded metals into the water. At the other end of the pH spectrum, high levels cause metals to “plate out” of the water, or form stains at the molecular level that discolor pool surfaces. Pools with high total dissolved solids are especially problematic for controlling stains because the salt content of the water is naturally high. Salt water is corrosive. Additionally, chemical compounds frequently behave differently in high salt solutions. To add to the problem, there is a growing body of evidence suggesting that plaster surfaces may be more soluble in salt water than in fresh water. Salt water pool owners, and those who service them, need to be especially diligent in monitoring water chemistry. Unbalanced water can facilitate the release of metals and surface staining, but what’s also true is that even pools with balanced water will eventually stain. Since metal levels in pool water are constantly rising, the...

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