Your meter has "maxed-out" which means the reading on the line you are plugged into is over 2000 (two thousand) and the meter is unable to display it. When you install a filter on that line, it should immediately come into a readable area, most likely under 100 G/S units.
Previous article: I install a filter, but the reading doesn't go down to 30 or below. What can I do?
Customer support service by UserEcho