If you don't want to open yet, you can just pour bleach/liquid chlorine straight into the pool around the perimeter. I do this all the time (not yet, my pool is till covered in snow and ice). Not knowing what size your pool is I cannot tell you how much, but I usually use one 121 oz bottle of 8.25% bleach at a time, I walk around the pool as it pours out. Check the next day. If water is not clear than I use another bottle, and 2 is usually all I need before the pool is clear, though the bottom and sides might still be dirty.