Walmart has HTH Stabilizer/Conditioner. This is what you will use to raise CYA. Use the pool calculator to determine how much to add. Put it into a sock, rubber band the top and tie off to the ladder or in front of the return. Go by every hour or so and squish it to disperse. Do this till it's all gone from the sock. Then you should assume the amount you have added is in the pool and dose according to the pool calculator for the level you added.
Which granules have you been using? They may or may not contain CYA but if they do, your CYA level is not 0.
Which granules have you been using? They may or may not contain CYA but if they do, your CYA level is not 0.