Hey UrbanMonk, thanks for your input! The Diatomaceous Earth is very dusty, yes. But the carbon filter I have came with a fabric sleeve to keep out most junk. I noticed a few days ago that the sleeve was starting to get a bit dusty so I blew a few hard breaths on her. Cleaned her right up. My fan is doing good for now on a slightly lower speed. No more horrifying sounds. Gonna leave the fan/filter as they are unless something major breaks down. I'll check the fan out after harvest and pm you if there is a ton of D.E. in her.
If it is at it's dustiest when you are applying it, then might be a good idea to shut air down while you are applying it and then turn it back on. As that stuff is "gritty" is why it works on the bugs, so just like the Sawmill I worked at the sawdust would do a number on the bearings even though they were "sealed" bearings and their life expectancy was a lot less than in many other factory settings. And I bet the fine particles of that stuff has jagged edges same as the bigger pieces.