The dilution for testing pH is to reduce the chlorine level in the sample. High chlorine (over 10ppm) can cause inaccurate pH results. pH is not like the other tests we run on our pool water. Most tests measure how much of something is in the water. pH is a measure of the net result of the effect of all the acids and bases and buffers in the water and has more to do with the ratios of pH influencing factors than actual amounts. Distilled water has no pH influence so the ratios stay about the same.

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