I'll be using vitamin c for my pool rather than absorbic acid. Absorbic acid is used at 2 lbs for a 20,000 gallon pool. Does anyone have any idea how much more vitamin c you have to use for the same results. I thought they were the same but after reading some posts it says vitamin c works slower and you need to use more. I do have 1 lb of absorbic acid and 2 lbs of vitamin c on hand. Any opinions?