Spray booms need only the slightest traces of grain – spray chemicals (for example) to kill legume crops. Boom Kleen cleans and neutralises all internal pump, hose and boom surfaces. It in fact etches all internal surfaces back to bare metal etc. But even though it completely cleans out any spray residues, Boom Kleen is harmless to grasses and crops. Use it regularly, at the beginning and the end of the season, and also between different spray programs. Note: Boom Kleen is a caustic substance. Handle with care. Shelf life should not exceed three years.