>Wouldn't a particle filter and a couple of demineralization/deionizer
>columns do the same thing at a lower cost? I've seen an RO before but
>never got any specs about them. How often do you replace the membrane,
and what is its cost. What is the pore size in the membrane? Is the
>water sterile as well as pure? Got any conductivity specs?
Well..... easy questions first, for mine it is recommended to change
the TFC membrane (thin film composite) about every six months, about
$50, but since replacement is based on hours of use and I only run it on
an as needed basis, I might get a year or two use with no trouble
(here's hoping). Prefilters are changed more often and include a micron
filter and a carbon filter (5 micron), I know other people who just use
a carbon block prefilter. Relative costs of deion/demin versus RO I
don't know, but it seems to me I saw ads for both in the aquarium mags.
I don't have conductivity specs, but it seems to me that someone on the
list had their unit tested recently. - Was it Bazz? My source was
Nature's Way in Sarrasota Fl 1-800-780-2320, I once had info from places
in Arizona and Cal too. Apparently common in the aquarium industry.