Opening Numbers

[SUNNYDAYS]

I copnfirmed this morning with my Taylor kit that the CYA was 100. Dumped about 12 inches of water and currently refilling. I hope to see the number drop to at least 70.

[SUNNYDAYS]

UPDATE

I drained 12 inches of water yesterday in my 16x32 pool with a deep end and replaced it with "Fresh" water. My Taylor test kit still says 100 CYa and the pool store says 105 CYA. Is it possible to remove that much water and still have the same CYA?

What is going on?

[chem geek]

If your average pool depth is 4.5 feet (which is usually the case if your shallow end is 3 feet and your deep end is 6 feet), then a CYA at 100 should get reduced to around 80 (even if your deep end is 8 feet, the drop should be similar). 100*3.5/4.5 = 78; 100*4.5/5.5 = 82.

The CYA test is hard to measure at the higher CYA levels as you can tell from the closely spaced lines on the tube at higher CYA. I suspect measurement variation or error more than anything else. Either that or the CYA was actually more than 100 (since 100 is the highest the turbidimetric test measures).

I would just do another drain/refill and you should see a drop.

Richard

[SUNNYDAYS]

Yes that will have to happen again. I too was thinking maybe the CYA was higher than 100. The lady at the pool store said their test goes up to 120 or 130 so I am wondering why their first test said 105 and did not read higher. Only thing it could be error in reading their test.

I will keep you up to date.