Hello, I opened my pool on Sunday and ran my tests. It seems that I now have a very low CYA level, <10. Half my water is new(drained below returns this winter). The water is clear with little to no debris. I have dumped in numerous bottles of bleach and have not been able to get it up to shock. I am still near 0-1 FC. I put in one of the pucks that the previous owners had left, it is in a floater. How many of those could I put in for shock? I figure I need some CYA anyway. Can I just throw them in the bottom? Put them in the skimmer? Drop them in the filter basket in front of my pump? Secondly, I have been dumping the pool calculator recommended amount of bleach but I have yet to see any levels near shock. Should I just do something crazy like double/triple that amount. Also, my CH is 0, is that normal?