bio media can be bought online or at some nurseries that carry pond products.
they look like - um... let's see - hollow balls with.... spaces, well, that
doesn't make sense... remember the unfinished space station from Star Wars?
Like that. Kind of. ;-)

what works about them is that they have lots of surface area for bacterial to
grow on, are easy to clean as their spaces and hollows are larger than those in
lava rock which can clog up.

Other stuff that can work are plastic curlers, shredded packing tape, vinyl
screening - all rough surfaces, with lots of space inbetween, easy to clean and
light to lift.


kathy :-)
A HREF="http://www.onceuponapond.com/"Once upon a pond/A