Off the Chart Cyanuric Acid

[BnaRealtor]

I added chlorine and three boxes of Mule Team.
Results:
FC 15.2
CC. 0
PH. 7.4
Total Alk. 100
CH 250

I followed the instructions for the CYA. 1/4 c pool water and 3/4 distilled water. From that one cup I took a sample and my reading came in at 35(x3)= 105. That's dramatically lower than the "off the charts" I was getting. Did I do that correctly? Happy it's lower but puzzled.

If this is the correct CYA now, then how high should my FC be?

Thanks for all your help. Please test my high school chemistry teacher I may finally be getting it...lol

[Watermom]

With a CYA of 105, your FC needs to be 8-15 ALL the time.

[BnaRealtor]

Tested FC again this morning before the sun was up. 13.5 ppm. A 2.0 drop overnight.

[PoolDoc]

Not huge; depending on whether you've been using the pool, or had a bunch of rain, could be normal. Or, with the chlorine up, you could be cleaning up debris somewhere.

But, check corners and crannies for algae or slime. And, keep your chlorine up (15 ppm) up for several days, and see if the overnight loss drops.

[BigDave]

... 1/4 c pool water and 3/4 distilled water. From that one cup I took a sample and my reading came in at 35(x3)= 105. That's dramatically lower than the "off the charts" I was getting. Did I do that correctly? ...

Bringing bad news - Sorry!
Diluting 1/4C pool water with 3/4C distilled, we need to multiply by 4. The pool water is a quarter of the volume we're testing. The result is CYA = 35(x4) = 140. Sorry.

It's OK to run the pool with CYA that high, just need to keep FC high enough.

[BnaRealtor]

I though it should have been x4..... Oh well. Now I I have misread my ph and adjusted it too high. It's at least 8. Guess I need to add music acid to bring it down? A small amount is what I have read.