aim 5.0-5.5 rather than 6.0 if clones, really just as long as its below the hard zone.
I've been using the small packets that came with my meter for a month.
If you maintain your stuff and clean it after each use and store it in a neutral buffer the probes can last a couple of years. Usually this doesn't happen, and the probes only last about 6-9 months.
I've been using the small packets that came with my meter for a month.