Algae popping up on edges so I figured I need a chock. Funny I started the year with a CYA of 0 and now its up so much, now the shock level is sort of crazy! I have the powder shock and pucks from the pool store I wanted to use up but now I truly see how they change all my levels. I just added 10oz baking soda to raise TA and pH and 2 jugs of bleach to shock (thats all I have on hand). If those pool chemicals raise the CYA so much, how can they get away with that, do people really just drain their pools and refill everytime the CYA gets too high from the chems?