also, pH of 8 is pretty high- you probably want to add acid to drop it to 7.2-7.4... the shock levels of chlorine will throw the pH test off, so you can't accurately tell what it is while shocking, but it probably isn't going down any so adjusting now would be good

MA can be found at Home Depot/Lowes... think HD is cheaper (2 gallons for $10?) haven't bought any this year yet...