Treated stains with Vitamin C powder- How long till chlorine starts to stay active?


Apr 26, 2015
Denton Texas
Hi everyone

I have a 15k gallon sand filter pool. I got the bright idea to treat some stains in my pool with a 2 pound bag of powdered Vitamin C about 10 days ago. I thought I followed the instructions correctly, but I got little to no results. Now the free chlorine level is next to nothing due to the Vitamin C affecting it and burning off the chlorine. I have been adding chlorine at night every other day and let the pump run all night, but the free chlorine is not staying active.

I have been draining some water out and refilling every couple of days along with backwashing, etc to try and get this situation to end. Anybody know how long that Vitamin C will remain in the water and what other steps I can take to resolve this headache?

Thanks in advance


TFP Expert
LifeTime Supporter
Jun 12, 2009
NW Ohio
You have had zero chlorine for the past 10 days? That's not good.

Well, the problem might have started because of the ascorbic acid, but now it is almost certainly algae. That means the SLAM Process.

As for the staining, if it doesn't react with a vitamin C tablet being sat on it then it's either organic or a metal other than iron. If it is organic, the SLAM will correct it.