Sorry, been out for a while. I have not done the bucket test yet, but this is whta has happenned. I thre in some potassium peroxymonosulfate (fresh n clear) 3 lbs and water cleared within a day and a night. Stayed clear for about 3 days and now greenish again. All other values are same, chlorine at 6ppm. Anyway, I am being told that problem is sand filter cus it doesn't filter small microns and that instead of using diatomaceuous earth I need to use cellulose fiber, a de altenative because it filters smaller microns...any comments on this??