A stable, aqueous suspension concentrate which includes a solid polymeric dispersant comprising one or more anionic polymeric dispersing agents, optionally a co-dispersant which preferably is a homopolymer and/or a copolymer of a heterocyclic vinyl lactam, preferably in a wt. ratio of 0.1:1 to 1 :0.1 , a UV-labile, water-insoluble biocide active, and a UV-blocker or UV-absorber to stabilize said active upon storage and/or exposure to sunlight or UV radiation.
