No Chlorine Detected for Weeks, but Water is Crystal-Clear

[pgroux]

Hello, all! We have a 16,000-gallon pool in central Florida with a Hayward AquaRite salt chlorine generator. We seldom use the pool and the AquaRite seems to keep the water crystal clear. Every couple of weeks, I take a water sample to our local Pinch a Penny and, after they test the sample, buy whatever they say we need.

On the last three visits -- July 3, July 23, and July 26 -- they have told us (on each visit) we have zero total chlorine, zero free chlorine, high pH, high acid demand, low total alkalinity, low calcium hardness, low stabilizer, and low salt. I trust the Pinch a Penny guys, and even went to a second nearby store to get a second opinion, and got the same results.

The AquaRite is reading 3,400; I'm told it should be about 2,700.

My confusion stems from this: Our water is crystal-clear. If we have zero chlorine, high pH, high acid demand, and the other results listed above, wouldn't our pool be loaded with algae?

Would greatly appreciate anyone's / everyone's feedback.

Thanks in advance!

[PoolDoc]

Interesting. There are several possible explanations. But without actual test result NUMBERS, and some additional information, then I can only guess. I think I'll pass on that option for now. But, I can offer some recommendations.

1. You may trust the PaP guys . . . but I don't. We've occasionally seen totally bogus test results generated by PaP shops. That doesn't mean YOUR shop is doing so, but it means you don't know. The rule of prudence is "trust but verify"! Get a Taylor K-2006, VERIFY their results, and POST the numbers you get: K-2006 from Amazon (http://www.amazon.com/exec/obidos/ASIN/B004BGF7TI/poolbooks/).

2. Make sure you have no copper (= old heater or mineral/ionizer unit) in the system. That's not likely with high pH, but you should check.

3. Verify that your Aquarite is generating, by grabbing a test sample from a return water jet WHILE the unit claims to be operating . . . and then testing it YOUR OWN SELF. (Chlorine samples can disappear on the way to the store, through various mechanisms)

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Now, a single guess (among several candidate 'guesses'):
1. Your Aqua Rite unit IS generating.
2. Low stabilizer means chlorine disappears as soon as the sun is out.
3. Also, your testing procedures + low stabilizer means you never get positive results.
4. You have very low phosphates and/or high borates as result of past PaP chems (or fortunate accident, in the case of low phosphates).
5. Consequently, the chlorine added at night -- which disappears during the day -- is enough to 'do the job'.

As in many other areas of life, being 'lucky' is often better than being smart! Sounds like you are currently quite lucky in your pool's operation.

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[PoolDoc]

Upgraded membership and moved thread to the Algae section. You may need to log out and back in to see everything.

[pgroux]

Thank you! I'll order the K-2006, test, and report back. Greatly appreciate your help!

[PoolDoc]

:)