CYA Test with Taylor K2006 - CYA over 200!

I just received my Taylor test kit this week and made my first tests. I already knew I had CYA over 100 (pool store results) so for my first CYA test I used a 50/50 mix. That is, 50% pool water sample mixed with equal amount of tap (non-CYA) water. The results for this attempt was 100+ of CYA (watching the black dot disappear, etc.). So I started over. This time I repeated the 50/50 mix. Then I did it again - I took to 50/50 mix and mixed it again with equal parts of tap water. So now I should be at a CYA of 25% of the pool sample. Someone check my reasoning here, am I on the right track? Any way, the CYA test results with this 25% mix came in at CYA of 50-55. Doing the math, my actual CYA is 200-220! We are deciding when to drain the pool, end of this season, or now. We haven't decided. Here are the rest of my test results.

FC=.6
CC=.6
pH=7.1-7.2
Alk=90
CH=60
CYA=200-220
water temp=87

I not sure I believe the CH numbers yet. Most of the pool store readings for my pool have been in the 450 to 550 range. I need to recheck my CH (btw, our fill water is very hard at 19+ grains or 324.9ppm if I used the correct conversion)

[Edit - Pool store measures and reports Total Hardness, I only tested for Calcium Hardness. Now I'm worried my CH is too low]

Yeah, I think your logic is fine on your CYA test. It's subject to a lot of inaccuracy from the dilutions but I think you're close.

If you have a water softener, you could limp by the rest of the Summer then drain and refill through the softener solving both CYA an Ca issues. (keep your chlorine up)

There's at least one potential problem with using tap water as your diluter. The CYA test is basically a turbidity test. Any turbidity in your tap water will add to that resulting from the interaction of the test reagent and the CYA in the pool water and may give you an inflated reading. (I think.)

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Originally Posted by KurtV

There's at least one potential problem with using tap water as your diluter. The CYA test is basically a turbidity test. Any turbidity in your tap water will add to that resulting from the interaction of the test reagent and the CYA in the pool water and may give you an inflated reading. (I think.)

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If that were true, then wouldn't most CYA tests would be invalid since tap water is used as fill water?

I don't think so. I imagine that the sediment (or whatever was causing the turbidity in the fill water) would be filtered out and/or oxidized. I suppose that cloudy fill water could give a falsely high CYA reading temporarily, but not once you had the water cleared up.

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Originally Posted by duraleigh

Yeah, I think your logic is fine on your CYA test. It's subject to a lot of inaccuracy from the dilutions but I think you're close.

If you have a water softener, you could limp by the rest of the Summer then drain and refill through the softener solving both CYA an Ca issues. (keep your chlorine up)

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Clarification - The "tap" water I used was actually filtered water from my RO system.

:eek: I thought my CH was too low at 60 ppm.

I think I need to bump my Calcium up some. BTW, I do have a water softener, and that is exactly what we did about three years ago - we filled the pool partially with softwater (if I remember correctly it was approx. 50% soft, 50% hard).

Yeah, I sorta' jumped to the conclusion that your CH test result was erroneous.....

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Most of the pool store readings for my pool have been in the 450 to 550 range. I need to recheck my CH

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Certainly, if your Ch is 60, more Calcium is in order.