JasonLion said:1) Don't assume it will be a short time, if you are not adding enough chlorine it can be a very long time. And don't assume that the SWG will ever catch up on it's own. You need to raise the FC level up to measurable levels by manually adding chlorine, how ever much chlorine that takes.
I did not assume it would be a short time, I was just going by what Chem Geek said just below your post above, "If there was leftover ascorbic acid, then that would certainly create a chlorine demand, but it would be very fast so you wouldn't be able to add chlorine and pass the overnight chlorine loss test." Every day I would add enough chlorine to get up to 8 to 9 ppm. No loss overnight, but no gain either. Never went below 3 ppm except for that 24 hours during the AA treatment at which time I had 2 quarts of polyquat in the pool.
I also did not assume that the SWG would ever catch up. I am aware that if I get close to the lower FC limit I have to manually dose. I was manually dosing up to 8 to 9 ppm during the three weeks that this was occurring. Never did I just let the SWG try to catch up.
JasonLion said:3) Then you had a low level algae problem, presumably started because you failed to raise FC levels quickly enough after the AA treatment. The period after an AA treatment is a balancing act. You can't add chlorine too quickly, nor can you add chlorine to slowly. You have to establish a minimal FC level by the second or third day or you are certain to get algae (which may or may not be visible). And once you get algae it is common for the SWG to be unable to deal with it on it's own.
I thought I had an algae problem also, that is why I did an overnight test three times over three nights. CC was .2 or 0, water has been clear the whole time this has gone on and <1ppm loss overnight. Remember I had 2 quarts of polyquat in the pool during the 24 hour AA treatment. I then added 5ppm chlorine after 24 hours.