landey1230,
Potassium permanganate (PP) from what I understand is a powder or crystaline form that is used in water treatment facilites and by water softener companies. In ponding I have read that people use it to do a number of things like disinfect newly acquired plants before adding to our ponds, treating fish for ulcers and parasites (very mild dose), and clarifying water. It supposedly leaves a stain that is impossible to remove if spilled on the floor, kitchen counter, etc. I found a lot of useful info on its use and dosage from a link provided by another member of this board. Since I cannot remember the post itself, here is the website it is on:
www.koiphen.comand search "Potassium Permanganate".
A number of people have accidentaly killed their fish by using this, so you might want to thoroughly read the technique and dosage recommendations made on that site before using it.