I originally started buying blanket weed killer from this seller and was so pleased with that product, I decided to try this one as well, and I have been very pleased indeed .
I have no,idea "where" the sludge disappears To, but it does, and quite quickly.
I am very pleased to recommend this product to anyone else with this problem in their pond,
Oh! I would add that I have several fish in my pond and neither product has affected them one bit. ;0)