CYA testing

[KirstenHW]

On Friday I received my replacement reagents from Ben for my Taylor K2006 kit. I was excited, as it had been a while since I had any CYA reagents. I had 3 floaters with 3 pucks in them about 3 weeks ago. I thought my CYA would have gone up, but it hasn't. I can't tell how much I have in the water. When I ran the test Friday, the dot disappeared when the tube was completely filled with test water - there was a meniscus (sp?) bulge at the top. The last mark on my kit is 30 - what should I assume my number is? My FC has been holding for about 3 days at a time at between 3 and 5 ppm - which has been ok, even with the extreme heat and all the rain we've had in the northeast (not to mention the tornado that plowed through the building I used to work at in Valhalla NY). I am trying to not depend so much on the pucks - last year my CYA went way too high. Plus I have only 4 left and am feeling too frugal & lazy to buy more . . . :rolleyes:

[KirstenHW]

Can anyone tell me what to do about my CYA level? Should I just assume it

[geordie]

I think we're not replying because we can only guess along with you. I am actually noticing this year that my CYA isn't increasing at the rate it has in previous summers, and in my case it definitely can't be becuase of rain.

I think the best thing to do is start with the premise that you clearly have enough CYA since your chlorine is holding and at what is probably an appropriate level. If you are showing 30 then even if you are off and higher than that, you can look at the chlorine chart and figure that for 30-50 CYA you should be maintaining 3-6 ppm of chlorine. Sounds like you're right there, but re-testing in a few days may give you some peace of mind.

[KirstenHW]

Thank you, Geordie!

[hulla]

Your "glassware" only tests cya up to 30? That doesn't make much sense to me since 30 is at the low range of normal. Or even too low.

[chem geek]

Your "glassware" only tests cya up to 30? That doesn't make much sense to me since 30 is at the low range of normal. Or even too low.
Most test kits that test for CYA have a measurement tube that starts at 100 at the bottom (i.e. adding a small amount of rather cloudy liquid will obscure the black dot) and often ends near the top of the tube at 30 (i.e. it takes a lot of liquid to obscure the black dot).

KirstenHW found that it took even more water than filling the tube to the 30 level line and that continuing to fill the entire tube beyond this last calibration mark had the black dot go away. In my Taylor K-2005 kit, the 30 line is close to the top of the tube and much closer to this tube top than it is to the 40 line below it. Since the scale is logarithmic, filling to the very top of the tube is probably a CYA of around 27-28 ppm.

A CYA of 30 is not necessarily too low. It's partly a matter of taste and how much chlorine reserve you need due to the amount of regular chlorine loss you have. I run my pool at around 15-20 ppm CYA with lower corresponding 2-4 ppm FC levels, but I only lose 0.5 ppm FC or less per day since the pool is covered most of the time (it's an electric opaque pool cover).

Richard

[hulla]

Most test kits that test for CYA have a measurement tube that starts at 100 at the bottom (i.e. adding a small amount of rather cloudy liquid will obscure the black dot) and often ends near the top of the tube at 30 (i.e. it takes a lot of liquid to obscure the black dot).


Oh yeah, thanks for clearing that up.