A minor nit on Joe's last post. It may be possible to run some pigment inks through a ,48 um filter or even a .22 um filter. I understand that some pigment manufacturers mill their pigments down to less than 100 nm in order to improve glossiness. (or at least that's how this old fart remembers it ...) So it's possible that some high quality pigment inks might pass a .48 um filter, but don't be shocked when some bargain priced 3rd party ink doesn't.
I am only considering 3rd party pigment inks here. Yes, OEM pigments may indeed be ground to nn size particles BUT they ( in the case of EPSON K3 ink ) are then microencapsulated in resin which increases the overall size of each particle. That is the true reason for their better glossiness. The smother the surface of the printed layer of ink, the less, light is scattered so the glossier it appears to the eye.
The more "Bumpy" or rough ( due to NON micro encapsulation ) the more matte or less glossy it will appear.
So yes a larger pore size might allow a certain proportion or these particles to pass. But you know, why bother.
The damage may already be done. That why it is important to not hoard ink from 3rd party providers.
Whether or not it can be "Cleaned Up" by filtering, you can not remove the Waste metabolic products already generated by those little bugs and fungi that now happily growing there!
The bio solids are already trapped by the Print Head nozzles, thoroughly burned into them sooooo...
Time to spend money on a new head and new inks. Then make sure you use aseptic techniques when loading and use up the ink before a years end.
What? You say you do not print often enough to use up a 4 oz set of dye inks within one year? Then maybe you ( Speaking generally here ) should give up on home printing and begin to farm your printing out to local lab. Or if you really do not print but once a month, then OEM inks would be a better choice.
Joe