I am in the process of shocking my pool and the water remains cloudy. I have not done an overnight test yet but plan on doing it tonight. My biggest concern is that I see sand at the bottom of the pool more concentrated where the returns are. Is there a reason as to why this would be happening? We had a small amount last year, but this year it seems to be more. Also, in the past years we have had very high cya levels. Last year we had it at about 50 or 60 and now the first reading and subsequent ones have shown zero. I am scared to add cya due to the fact that we had issues with it. Can I add sticks and turn them up in order to get cya into pool? If I can how long do I wait to recheck it. Any help with my questions is deeply appreciated. Thanks!