"things" = chemicals, solvents and the like.
think of those rinky dink lfs stores that keep their saltwater tanks decorated with colored substrate made for freshwater. in either case, many will bleed into the water, which can be for more toxic for the saltwater fauna than the fresh.
wow, talk about irony. cans made for janitorial purposes are the only ones that are food safe. gotta love those geniuses at rubbermaid
