Get a floater for the tabs, check out Walmart or Kmart for the aquachem test kit! If there is another pool store around let them test your water and compare the readings. When the metals read 0 ppm (or very close to it....not more than .3 ppm) you can procede with the water balancing and chlorine. The low pH right now is actually helping with the metals and is probably a result of the keetrol. As long as it doesn't get any lower then don't worry. If it does use Borax (20 Mule team in the green box from the laundry aisle at Walmart or the grocery store) to raise it up. Start with about 1/4 box poured into the skimmer and test the pH the next day. Repeat this process until the pH is around 7.2