What concentration or ppm should I use?

We can only make recommendations when it comes to ppm usage, and referring to research is best. Concentrations and ppm will depend on the application. 

The FDA allows concentrations of 30-60 ppm when sanitizing food such as fruits, vegetables, fish, and seafood without compromising its appearance or taste, with no harmful residues. 

General sanitizing for contact surfaces is effective at 200pm, however, you may safely use a solution of 300-450 ppm for infected areas. 

Hospital-grade disinfectant is mandated by the CDC at 1,200 ppm and is only intended to be used as such.