That doesn't make sense to me but I haven't messed with filters much. This is what I found using google:
Which Is Finer? One Micron Or 100 Microns?
It's easy to get confused when it it comes to filters. It's easy to imagine that 100 microns would be a better filter than 1 micron, but this is the exact opposite. Again think in terms of the hole size in the filter medium. If a micron is a unit of measure, then ten microns must be ten times bigger than one micron, and one hundred microns must be ten times bigger than ten microns.
So, if a filter is 100 microns, the holes that do the filtering are 100 times bigger than those found in a one micron filter.
Filtering In Microns Made Easy
Still confused? Okay, so I'm not a scientist and my explanation may be a little off, so here's a quick guide:
Coarse Filtering = 500 Microns, 200 Microns, 100 Microns
Medium Filtering = 50 Microns, 20 Microns
Fine Filtering = 5 Microns, One Micron