You should have two filters
A Racor primary filter (or 2) ,mounted on the bulkhead and a secondary filter mounted on the engine.
The primary filter is there to filter out gross contaminants and water...it should be 30 micron or min 20 micron.
the secondary filter on the engine is to remove any fine particulate matter and should be what the engine manufacturer recommends..10 or so micron normally.
The primary filter is there really to protect the secondary filter, and if you use clean fuel you should rarely have to change the secondary filter.
Using a fine 10 or 2 micron filter in the primary will just lead to more filter changes as they will clog up more quickly.
For example Yanmar recommend a 30 micron primary and 10 or 2 micron secondary for their modern common rail engines,
We have an ordinary old fashioned donk and use 30 micron in the primary and 10 micron in the secondary and always filter the fuel with Mr Funnel when refuelling.