Lee,

I only use my Buon Vino filter rarely, and am not an expert on
filtration, but from what I've read, it's not so much an issue of pore
size, but of the nature of the pores. A membrane filter is basically a
thin sheet with lots of uniformly sized holes. the hole size is said to
be "absolute", as there are no larger ones. A depth filter, like the
Buon Vino pads, has a lot of different sized holes or channels, which
have an average, or nominal, size. As Tom points out, since there are
pores larger than the nominal size, there's a certain amount of larger
stuff that gets past. Just because the pads are rated .5 microns doesn't
mean they will stop everything of, say, one micron. <sigh> It takes a
better tool than a Buon Vino, I'm afraid. Even if one could contrive an
absolute filter for one, it probably wouldn't have the pressure to work.

If anyone has found a way to do it, though, I'm all ears.

HTH, Mike MTM