Ascorbic Acid and Balance FC

[Gonzo3]

Can anyone provide any details on how long (or how much chlorine) it takes to re-balance the FC after doing an ascorbic acid treatment? I have a 23K gallon vinyl pool, and I may have gone a little heavy on the AA and use about 3.5 pounds to remove iron stains on the liner (panicked and added more when the stains didn't disappear). It's been over a week, and I'm still having trouble keeping the FC up. I was able to get to my target level after 2 days, but if I turn off the SWG, the FC levels drop pretty quickly. CC is 0 and the pool is crystal clear, but with the pump running 24/7, it's still been a challenge to keep the FC at target levels.

Thanks.

FC - 5
CC - 0
pH - 7.2
TA - 60
CH - 75
CYA - 40 (I know this is low. My first year with a SWG, so holding off to determine if I have to shock before raising)

 

[OTPirate]

The last AA treatment I did it only took a couple days to get my FC back in check. It should not take over a week. It is possible to have 0 cc and still have algae. My last two SLAMS I had 0 cc's. How does your pool look?

 

[Gonzo3]

The pool water is crystal clear, and it was clear before and after the ascorbic acid treatment. Because my CC is 0 and the pool is clear, I wasn't sure if the AA was still consuming the FC. I'll do another overnight chlorine test, and if it fails, I'll start a SLAM tomorrow.

I was really happy with how well the AA treatment worked, but it's a bit of a pain to have to deal with SLAMing the pool. I'm also worried about the iron settling back on the liner.

 

[Gonzo3]

I lost 1ppm of FC overnight (12 hours). It rained throughout the night, so I'm not sure if I should count this test as valid. I'll do another test tonight, and hopefully, the rain will stop before then.