Quote Originally Posted by kjsmom
I have a 23,600 gal vinyl liner inground pool. On May 1st Leslie's tested my water. Results were:
FC: 1
pH: 7.6
Alk: 80
CYA: 30

That day, I added 5 lb 10 oz of CYA. Today, 5/9, Leslie's tested again:

FC: .5
pH: 7.8
Alk: 100
CYA: 35

My test results, with my drop kit, indicate pH of 7.6 and Alk of 80. I cannot test for CYA. My question is, would it be possible that the CYA is still not dissolved? According to Michael's calculator, 5lb 10 oz of cya should have raised the cya 30 ppm, to 60, not 35. The water temp is 71 -- not too bad. How subjective is the CYA test? I've read that a dot has to disappear; is the cya test predicated on a color change? Could the results be off by 30ppm? That seems to be alot for cya. Thanks.
PAT
Pat, there's obviously a discrepency in the tests. Did you add anything that would have affected the pH and alk? Why did you want to raise your cya?? (30 is IMHO about the perfect amount).

The cya test is VERY subjective! Any 2 people can run the same test, using the same tester, and come up with varied results (the trick to doing your own testing is to be consistant when doing your own, if you're a little off on your testing methods - at least you will be able to adjust for it and dose the pool accordingly)
Best advice; get a good kit, compare your results to a 'known' -i.e. pool store's (though if they don't calibrate their equiptment regularly, it's useless), and see how well you are performing the tests.

CAVAT- pool stores' computer programs seem to be designed to sell chems, so use your own knowledge to decide what to add (or not add) when they tell you how many hundreds of $ of chems to buy, to correct a ~problem.