You will use up chlorine fast, because the chlorine is attacking the ascorbic acid. I don't know why your ph hasn't gotten any lower than that, mine always did - are you sure your ph test is ok? I also know that all pool water reacts differently sometimes, so as long as your ph is ok, just keep adding bleach and filtering. You can bump your filter, and backwash as needed now - I'm sorry I don't know anything about DE filters.