Pre bottling filter recommendation.

[Silk City Distillers]

Proof would need to be fairly low to be concerned about sterile filtration to prevent spoilage, but have heard of some microbes that can remain dormant in higher proofs, so ok - it's a factor.

Sub micron has more to do with light scattering as it passes through the bottle.  It presents more as a kind of very light opaque haze than as visible floating particulate.  Not talking about floc, clouds, etc.  

I've seen this with carbon filtration, where the spirit on the shelf has a kind of gray tinge, due to sub-micron carbon particulate.  Murky maybe?  I can pick it out pretty easy when I'm looking for it, especially in a bright store, with lots of bottles side-by-side for comparison.

To me, visually, sub-micron has a kind of sparkle to it.