At the beginning of the year, my CYA was off the charts, and my pool was a swamp. Combined with the de-swamping process I replaced some of the water (about 50%) to get the CYA numbers down. I had pucked my pool for the last 3 years, prior to finding this site.
CYA: 60-80? (hence this post)
CH: 890...yep, I know its a nightmare. Gotta love Cal-Hypo and fill water loaded with Calcium.
When I did the partial drain and refill, and got my TF-100, my CYA tested at 50. I have not used any pucks or "shock", or anything else that contains stabilizer in the pool. The other day, a particularly sunny day, I tested my CYA again and it tested at 90 or so. I thought that was a way high, and it was unexpected. I poured the reagent back in the squirt tube, and began again to slowly put reagent back into the view tube. Came up with 80.
Today, when I tested again, it is slightly overcast, I came up with 70. I have run this test over and over again, out of reagent now, and have to order some more. I put my back to the sun, put the view tube down at my waist, and I add the reagent until the black dot dissapears. I'm assuming that my CYA is somewhere between 60-80.......eliminating my extreme results.
I do follow the mixing directions once I add the reagent to the water in the squeeze tube. Mix thoroughly for 30 seconds. Set down for 30 seconds, mix again, then test. Back to the sun, view tube at my waist line.....
I wear glasses, and get a lot of glare in my vision when doing this test. I get lower results on slightly overcast days when I'm not dealing with the glare. I am also 6'4" tall. I have no idea what my exact CYA level is. I'm not that worried about it, I'm maintaining maximum FCs right now (9) and my water looks great.
Any suggestions or help would be great. What time of day do you all perform the CYA view tube test? Overcast? Slightly overcast? Full sun? Should I lift the tube a bit?
I have company coming in a week, and I do plan on doing another drain and refill to get that CYA below 50, but I don't want to harm my pool which is currently spotless. I'm not consuming a whole lot of chlorine...bout a gallon and a half a week...sometimes less depending on the weather. I'm kind of happy with the current condition of the pool, and somewhat reluctant to change anything right now.