MER-MAID automatic toilet bowl cleaner is the easy solution to keeping your toilet clean. It works hard so you don’t have to. If the water is blue, MER-MAID is working for you! Cleans and freshens your toilet bowl. It’s so easy! Just remove the yellow tab, place it upright it in your toilet tank and MER-MAID will clean your toilet with every flush for up to 3 months! CRYSTALLINE GEL; NOT SEPTIC TANK SAFE. Sustained-release technology releases the right amount of ultra-strength cleaning solution that breaks down stains and residue and washes them away.