Pet Warehouse
PO Box 310
Xenia, OH 45385
800-443-1160
It might be worth ringing them for prices or their catalogue. A good way
to get a feel for the market would be to get a copy of FAMA (Freshwater and
Marine Aquarium magazine) which has heaps of ads for RO units including the
above mail-order places. You could also check out an aquarium shop near
you, but they generally charge premium prices.
If you don't fancy buying mail-order, on the WWW there is a list of vendors
for RO units which might be useful.
http://www.actwin.com/fish/vendors/RO.html
Just for an example, one brand's smallest filter was a 15 gallon/day 2 stage
filter and that was $125. They said the prefilter should be changed at
least once a year, and the RO membrane should last 2-5 years depending on
your water and how much you use it. However it is quite possible that
someone might make smaller filters and I would guess that the big mail-order
companies would be cheaper???
Good luck,
Frank Udovicic
Canberra, Australia