I tested the pool at my hotel. At 15 secs the readings were 0.5 and 7.8. In about a minute or more, they changed to 1 and 8.4. Is 15 seconds the only time you trust the reading. From these numbers, they got better as the water stayed on the strip longer. What is the valid answer? Thanks.

Question:

I tested the pool at my hotel. At 15 secs the readings were 0.5 and 7.8. In about a minute or more, they changed to 1 and 8.4. Is 15 seconds the only time you trust the reading. From these numbers, they got better as the water stayed on the strip longer. What is the valid answer? Thanks.

Answer:

The test strips are designed to be read at around 15 to as much as 45 seconds. Once the time goes beyond that, the colors start to dry and typically darken. It is best to read them bewteen 15 and 45 seconds. Also at free chlorine of 0.5 and pH 7.8, these would be reasonably good conditions, although the chlorine should be slightly higher at around 1 ppm.

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