With a CYA of around 50, you want to keep the chlorine level between 3-6 all the time. If you dip below that, you risk an algae bloom. In this size pool, each quart of 6% bleach will add 2ppm of chlorine. Use that as a reference to help you determine how much bleach to add. Each evening, you'll want to test pH and chlorine. At that time, add enough chlorine to get the level back to 6ppm.

While you are refilling it, go ahead and add a little bleach. Every foot of water added, add a quart of bleach. By the time you have it filled up, that should be about a 3 quart jug having been added which should take you to about 6ppm.

With a CYA of 50, you won't want to use any forms of stabilized chlorine, meaning no trichlor pucks nor dichlor shock powder or else your CYA will continue to rise.

Although not critical, you may want to lower your alk a little to get it between 80-120 or so. Read about this process here: Lowering Alkalinity Step-by-Step


Also, read the "using muriatic acid safely" link in my signature below.