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Saturation index
The saturation index (Si) relates to the calcium and alkalinity in the water and is an indicator of the pool
water "balance". Your water is properly balanced if the Si is 0 ±.2.If the Si is below -0.2, the water is
corrosive and plaster pool walls will be dissolved into the water. If the Si is above +0.2, scaling and
staining will occur. Use the chart below to determine the saturation index.
Si = pH + Ti + Ci + Ai -12.1
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