In a 20K pool, each quart of 8.25% bleach will add about 1ppm of chlorine to your pool. You can use that as a reference to help you figure out doses of bleach to add. How high you need to keep the chlorine depends on what your CYA reading is. Take a look at the Best Guess Chlorine Chart in my signature below for more info.

You can pour the bleach slowly around the perimeter of your pool reaching as far from the edge as you can. Then, use a clean broom or oar or something to stir the water around as much as you can. Or, you can use a submersible pump.

Hope this helps!