Hydrothol 191 Granular 40 lb & 20 lbs Herbicide MSRP: Now: $129.99 - $198.00 Was: Hydrothol 191 Granular is our #1 Selling Chemical for killing submersed aquatic weeds weeds. It is extremely effective against a broad spectrum of submersed weeds and it also controls... MSRP: Now: $129.99 - $198.00 Was: