Wife and I have struggled with what we thought was dirt / sand coming out of the returns. We have tried everything, including changing our sand, but I'm finally giving in to the inclination that I have algae, and I think its Mustard. We have SLAMed twice, but we have never gone all the way through with the Mustard Algae process. And I'm thinking that is why it keeps coming back. In this last round, we have it sticking to the walls in the deep end and anywhere else that is the least bit shaded. We put socks on our returns and they turn yellowish / greenish color overnight. So I'm going to SLAM again and run the FC up to 24 per the CYA/Chlorine chart. However, my wife is REALLY concerned about bleaching the liner at this high FC level. We have vinyl liner. Are we completely safe to go for the 24? What can I say to put her mind at ease?