The 1/4 acre pond I had renovated last August, but not filled significantly until November, is amazingly clear, about 4 feet of visibility, easy. The small forage pond directly above it built November 24, stays muddy, with only about 4 inches visibility. After a big rain event, both are muddy, but the main pond clears up in a week or so, and the small one stays muddy. What could be the difference? Both were pump filled initially from the same creek. No alum was used in the main pond.