I think you probably didn't have enough HEDP in the water for all of the metal, by taking your ph up to 7.3 and your bleach up to 6 it caused the metals to fall out. You probably needed more HEDP, I usually keep the ph on the low side - about 7.0 to 7.2. I have been getting a lot of staining this year even with the culator. I think it is because this year I did not have my pool at the saturation point to have the calcium precipitate out. It seems if when you do the stain treatment, and your water gets cloudy, the metals seem to get filtered out with the calcium precipitate. It is just an observation right now. I am thinking of experimenting by doing this, but I am getting company and don't want a cloudy pool right now. I have been adding a little ascorbic acid and more HEDP when I see the stains start to come back. If you put about 2 cups around the perimeter of the pool, and let the pump on recirculate overnight it should lighten the stains. It will use up more chlorine than average, but it won't be enough to mess with your water balance too much. Make sure you use polyquat and keep your chlorine at the low end of the best guess chart. Take the tabs out when you use bleach. Make sure the tabs don't have anything else added - a lot of tabs do now. It might be where you are getting your metals. I know it is really frustrating, I have dealt with stains for the past 11 years. I used to try to figure out where the metals were coming from, but now I just deal with the stains when they come. I always keep some ascorbic acid and HEDP on hand. I know how you feel, I hate stains too!