Summer, don't worry - put the whole bottle of metal out in and keep your filter running 24/7. When you put fill water in, put it in through the filter. Lower your ph down to 7.0 - 7.2 - You can do this by getting a sock and filling it with ph down, tie the sock to your skimmer pole, and rub the stain with the sock - it should take the stain off, as well as lowering your ph just a little bit. Don't worry about putting in too much metal out - it won't hurt anything, then any metals that get into the water will be suspended in solution. Sometimes just adding the metal out and lowering your ph will take a new stain off, but rubbing the stain with the sock of ph down will do the trick, or You can aslo use ascorbic acid in the sock if you have any left without messing with the chlorine.. Let me know how you do, I was just as scared as you when I saw the stain return after doing the whole treatment, but you will see that once it is gone, and you keep your water balanced, you should be fine.