If you do indeed have copper in your water, then yes you do need a product that sequesters metals before you shock it--go to the metals forum and you can read about it--in order to keep the higher chlorine levels from causing the metals to drop out and stain your pool. If you don't have copper or other metals in your water, then you don't need it. Did the other store test for metals specifically? Have you used any algaecide containing copper? Or trichlor pucks made by hth and sold at WalMart? These are all sources of copper that could have been added to your pool since the last test.

Your pH and alk are fine, can't advise you about calcium until I know what kind of pool you have--if it's vinyl, then calcium is irrelevant, but if it's concrete/plaster, then it's way too low. You do need to get some chlorine in the pool, though, because if you don't have a problem now, you will shortly. How much chlorine is going to depend on your stabilizer (CYA) level and whether or not you do have copper in the water

Janet