You need really heavy filtration to get them out, solid current so all the particles are airborne and will travel and be sucked through the filter, not just washing around in the tank (like mine currently - sump under construction to fix that).
This bugged the hell out of me as a photographer, so I looked into and found the solution for it. LFS should sell high flow 50 Micron Filter 'Wool' I guess you would call it, and if my memory serves me correctly, 50 microns is 0.005mm, so there won't be any particles getting through that. Put this into the top of your canister right before the impeller, so all slightly larger particles will get filtered and stopped by your previous mechanical filtration, and then the last surviving 'specs' will get trapped by this stuff. Downside to crystal clear water is that you're going to have to clean the wool out more often than you would usually clean the filter, but in my opinion it's worth it.
Seachem Purigen is another product I highly recommend for water polishing, 100gm bag is cheap, reusable, and polishes around 100Gal/400L effectively. I'm running 200gm on my 140 and the water, apart from specs and dusty/cloudiness when stirred up is crystal clear.
Hope this advice helps, let me know how it goes as my sump is going to have a lot of mechanical filtration in it so I don't have to use Photoshop to remove so many specs
