I just rinse mine with tap water before putting the cap on, works for me. Get yourself some calibration solution so you can check it every once in a while to be sure of accuracy. I probably check mine every few months, never off by more than .2
Just read what the manf. says. My blulab says to keep in tap water. I let one ph meter dry out a while back, had to constantly fuck with it. It never gave me right reading after that.