"I too am interested in this discussion. I tried prefiltering through some mesh and it seemed the pollin just broke up smaller and went right through."

that is my conclusion also - I don't think that any screening will filter out pollen - nylon stockings ? maybe would help if going thru several layers - I don't happen to own any, so I will leave testing up to someone else.

Obviously, the more pre-filtering you can do, the longer the filter cartridge will last, regardless of whether you are using a pump filter or a gravity filter.  That is why I use coffee filters on the intake line of my pump filters, and did wrap one around the filter cartridge - it needed two to completely cover the cartridge, and I should have been using two from the start, but didn't.

Dissolved sediment is so fine that it pases thru all of the pre-filtering methods mentioned and gets caught in the pleated filter cartridge.  As I noted in a post above, it was clearly passing thru the nylon "screen" that comes as a pre-filter with the cartridge.  You cannot look thru that white nylon (or plastic? not sure) - you can blow thru it - a small sponge is provided with the cartridge to wipe off the  white screen - I could not see that there was anything to wipe off when I did clean it.  I could see that coffee filter was trapping silt or pollen, as it was at least slightly dirty when replaced.

the amount of pollen in the water varied from lake to lake - some lakes seemed to be almost pollen free, while others had a skim of yellow on the surface, and sometimes, when the sun was right, I could see suspended pollen in the water going down for several feet.

as I mentioned in the original post, the reviews I read were varied - some people had no problems, and others, including a few for BWCA  said that thier filters clogged after only a few days use

regardless, the filter worked well enough to be included on the next tandem trip.  I don't think it is worth bringing on a solo trip for me - I don't base camp - maybe if solo and base camping it is still worth bringing, as no matter how slow the filter runs, it works all the time and will give you your filtered water if you have the time.  I don't see that the extra "hassle" with the gravity filter outweighs the minimal work of pumping a gallon and a half per day for my solo tirps.  Likewise, I could spend more effort in pre-filtering the water before it goes in the blue bag (its gotta help a little, at least) - and/or go out to the middle of the lake for water, but that extra effort seems to me to be more hassle than just pumping, and accepting that the cartridge may only be good for one trip.  Keep in mind that on this trip, we typically hit the campsite after 6:00 - several times it was more like 7, and once it was 8:30 - don't really want to fool around that much for water when you hit camp that late.