No Chlorine loss at night, HIGH loss during the day. CYA good

[Nickmpower]

I was at 5ppm last night, 5ppm when I checked it this morning. Now a few hours later it had dropped to 2. CYA is 45

I completed a slam several days ago because of overnight chlorine loss (no sign of algae and water looked great though). My water temp was very high, about 94, and the slam took I believe 3 days. Afterwords I had to do another asorbic acid test for stain removal. Instead of bringing the chlorine up really slowly, I just added chlorine till it would hold at the normal level. I wasn't about to let the warm pool sit there for days with hardly any chlorine, then just have to do another slam, and another asorbic acid treatment, and repeat.

Could the daytime chlorine loss still be something with the asorbic acid? Like the asorbic acid and chlorine reaction only happens with sunlight?

Another thing to note, is that several weeks ago my total alkalinity was 120, and now its 240. I am currently aerating and working towards correcting. I did a couple stain treatments over that time and I believe the asrobic acid brought down the ph but not the akalinity. Then when I added soda ash the levels of both the ph and alkalinity were increased. The ph has always been balanced except immediately following the asorbic acid. Could the chlorine loss be increased by the high alkalinity?

The water could not be more clear. The temperature now is down to 85.

 

[JohnT]

How confident are you in your CYA testing? Occam's Razor would say your CYA is too low. It's the most difficult test by far, and I'm never even sure I'm doing it right. Check out Pool School - CYA to ensure you are being accurate before you spend a lot of time chasing the problem.

 

[atttech-2]

I am loosing about 3 PPM in a full day in Tracy, 3 in a few hours sounds excessive perhaps you lost a little to sun and the rest to testing variance. What kind of test are you using to get the numbers? If it's an FAS-DPD try using a bit more of the powder might even want to do the 25ml test once just to see if it comes out the same.

 

[Nickmpower]

I had it tested a few times by different people at the pool store, same with the alkalinity. Strips AND reagents. Unless the shocking or asorbic acid could have brought it down, I did have it tested after that though as well.

I know that my chlorine testing is good because when testing after adding chlorine, the new level makes sense with how much was added.

Also phosphates are high at 2000, though I know this shouldn't matter if the chlorine is kept up properly