Hi. KNO3 is a complex or "salt" made up of K+ and NO3-. The 2 separate components are oppositely charged ions which are combined in the solid form. In water they "disassociate" or break apart. Both are vital plant nutrients --Laurel Laurel Merrell 4th (and final!) Year PharmD Student University of Washington http://students.washington.edu/merrell/aquaria.htm