Klenk's Bathtub Epoxy enamel

[jws444]

Usually 100% non-toxic means that it's food safe. There should be no anti-fungal or anti-mildew (arsenic) agents in epoxy. Epoxy is a non porous resin, so there should be no reason to add any chemicals to repel mold. People who build wood tanks use marine expoxy without any issues. As for "great stuff", that's polyurethane based. It foams up as a filler so I hope you're not using it as a glue of sorts. Are you trying to insulate your pipes that are underwater?