"Snooze" wrote in message
m...

"CanadianCowboy" wrote in message
.. .
Just wanted to share a very inexpensive Bio Filter with some mechanical
filtering that can easily be built at home.

http://www.mvwgs.org/filter.htm

Good filter design, I made mine out of 2 milk crates, two costco bulk
packs
of green scotch pads, and a few yards of gazebo screening fabric. I and a
fairly significant portion of this newsgroup do not recommend using lava
rocks as filter material. The pores clog up quickly and are difficult to
clean, they are heavy, and do not have a good volume to surface area
ratio.

Consider removing the rocks, and using sun screen fabric, which you can
get
from any hardware store. When it's time to clean the fabric, just spread
it
out on the lawn, and hose it off. Light, easy to clean, cheap.

-S

The lava rock is not meant to act as a mechanical filter. It holds bacteria
that eats up the fish waste. So in a sense you want it to 'plug' up. Some
people use broken up plastic spoons or Styrofoam bits for this (which you
have to contain with something like plastic netting). You should not be
using a pump that has to have a mechanical filter in front of it to keep it
from being clogged. You should be using a waterfall filter for this type of
set up. If you use the other type of pump then you do need a filter on the
front end and this does have to be cleaned (but even it holds good bacteria
so don't clean it with anything but pond water).