They are still aound, but not very popular any more. They got a lot of bad
press when fanmcier (and much more expensive) alternates came out.
Undergravel filters are still a great low-cost option for drastically
increasing your biofiltration capacity. In my experience, they excel in
freshwater tanks, but are mediocre in sal****er.

However, you need sufficient water flow through the gravel. A decent
air-lift will do great if you regularly vacuum or stir up the gravel to
prevent "mats" forming and binding the gravel together. The gravel should be
stirred or vacuumed every week or two to ensure that it hasn't matted. Some
people have reported problems using undergravel filters when they have live
plants - they either can't keep the plants alive or clog the UG filter. I
simply put my plants in
shallow pots - this gives the plants a place to anchor, and provides
boundaries for the vacuum (I don't vacuum the pots so I don't disturb the
plants roots). It also makes it a lot easier to apply fertilizer (if you
want to).

I always use UG filters in all of my freshwater tanks. My filtration typical
setup is an UG filter and a canister (for particulates not biofiltration). I
have tanks from 5 gal through 125, and haven't had any water quality
problems. I use two lift tubes per UG filter, and make sure that there is
good airflow (small bubbles provide more lift per volume of air - as the
stones clog, you need to clean/replace them).

My personal opinion regtarding the decrease in popularity of UG filters is
because the sellers simply don't make as much money on them, and many of the
aquariasts today want things with a high "gizmocity factor". A UG filter is
simple, doesn't require much maintenance, and does what is supposed tp. But
it doesn't look impressive or give bragging rights about the $X,000
filtration system.....

-JD


"John DeBoo" wrote in message
. ..
Years ago I had two of these and they worked well. What books I've read
(published 1995 to date) seem to say they are good inexpensive filters to
use. However, in my trips to WalMart, a local fish store, Petco &
PetsMart, they seem to have all disappeared - else I'm blind.

Are these little hummers still available? Thoughts & comments on them
welcome.

Grandpa John