Nothing in pool not even a ladder and the steps are built in. I'm almost certain its algae. I just bought a truckload of bleach and am currently shocking. I am familiar with the sediment you are referring to as I deal with that almost every day due to trees and the layout of the yard constantly keeps Crud in it!! But it was clean at 7pm last night and green stuff all over again this morning and when I brush it away it is a yellowish cloud. I just dont understand why as I have stayed ontop of it, or so I thought! I did leave the polaris in for a few days only operating it a few hours a day. Should I remove it imediatley after use? I wouldn't think that would be a problem?