You can use dichlor since it does have CYA in it, but it will take some time for your CYA level to increase. After you get the CYA level up to around 50 or so, you'll want to discontinue dichlor and only use bleach or liquid chlorine.

Now -- before you put the dichlor in, give us the package ingredients. Some places sell dichlor that is blended with some stuff that you do NOT want to be put into your pool. Also give us the Brand and product name.