I leave it for about 5 minutes. You should see it stabilize. You need to make sure you are using both a low solution (like 4.0) and a high solution l(like 10.0). It should not matter if you leave it too long (within reason).
After I calibrate I stick it back in the solution to see it set right on 10 or real close on a 10 solution. Also, make sure yiou rinse between solutions in some
RO water.
