Swimming Pool Secret #3

Still Adding Calcium to Your Liner Swimming Pool? Why?

Because your dealer sells it to you, that's why!

If you like contributing to your dealer's vacation fund, stop reading now. If you keep reading, you're likely to discover just how useless adding calcium to a liner pool is!

"Calcium increaser" -- actually, calcium chloride -- is added to maintain calcium carbonate saturation levels, as measured by the Langlier saturation index, which is an empirical index calculated from the pH, temperature, ionic solution strength, and total alkalinity and calcium hardness levels. Using this index is subject to considerable debate among chemists about its applicability to open systems such . . .

Wait, let's try that again.

Concrete pools are almost always lined with a mixture of marble dust and white cement. Marble dust is pure calcium carbonate, AKA, limestone. Water dissolves limestone, if it has a chance.

Naturally, if you've spent thousands of dollars adding limestone to the sides of your pool you'd like to see it stay there, so you add somewhat expensive pool store calcium to the water, so it won't grab the really, really expensive calcium you've got on the pool walls. But, if you don't have any limestone or marble dust on your pool wall, you don't need to protect it!

'Nuff said!

Guess what? This information applies to fiberglass pools just as much as it does to vinyl liner pools. (But not to fiberglass coated pools!) One thing to remember, though: low calcium doesn't hurt pool liners, but low pH does. To be safe, make sure you keep the pH in your vinyl pool above 7.2!

For you engineers, there is some evidence calcium protects metal equipment made of steel or iron. But, there is little evidence that this is so for copper or brass components found in pools built in the last 15 years. Of course, you don't want to operate at an acid pH, either.

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