I added ascorbic acid to my fiberglass pool a couple of weeks ago and got rid of all my stains but can't seem to get my free chlorine level up! I thought I had a handle on it with bleach and raising my chlorinator to 100% but I came back from being gone for the weekend and my level is back down to 0. But my Total Chlorine is at 3! I'm so confused. I don't even know the difference between the two!!