Steripen prefilter

If by “works”, you mean “does it filter out mosquitos, sticks, sand, and small fish”, then yes it works.  But it is a 40-micron filter so it does nothing for suspended clay particle and very little for silt.  The toe of a nylon stocking and a rubber band will do as well, and be cheaper and lighter.  Using a corner of your cotton bandana, which many of us travel with anyway, works as well on chunks and better on silt.

That’s a weird link. Did you mean this: https://www.rei.com/product/784450/steripen-fitsall-filter

I’ve used this in my wide mouth bottles and works well for getting the floaties out of mountain lake water. Somethimes you need to pull the blue tab (or spout or whatever it’s called) up to allow air flow.

-Barry

A mosquito headnet folded over a few times makes a very effective pre-filter.

Of course, if you’re in Alaska getting attacked by squadrons of Cessna-sized skeeters while collecting water, well, that can be a tad inconvenient. :^)

I don’t obsess about floaties but I know a guy who’s used these for several years and swears by them:

https://www.dudadiesel.com/choose_item.php?id=PTFEP3S

Cut out the ring that gives shape to the top and it’s not heavy in a UL sense, maybe questionable for SUL.