If its half strength you might have to leave it in longer.
PS: Have LOTS of baking soda, I ended up using 4 med size boxes and 2 small ones I had in the cabinet. Could have potentially needed more.
USE Protective equipment, gloves (arm length), Safety glasses, mask (fumes), spill catcher as it will definitely spill over (FOAM).
Take your time and don't rush, ACID is nothing to play with or cut corners on.