David,

As for whether it is best for the water to run upflow or downflow, a well
drained downflow, free to allow air into the media is probably the best and
is known as a trickle tower. If the filter is full and used for plants on
top, then upflow is easier to plumb and maintain a water level. The
bacterial surface area is the same, the difference with trickle tower is the
additional aeration available.
--
RichToyBox
http://www.geocities.com/richtoybox/pondintro.html


"David Larson" wrote in message
...
Hello all. What a great resource!!!

I am building my own pond filter (150 gallon) and am not sure about water
flow through the chambers.

The filter will be a three chamber style - one to settle out the big stuff
and two for
bio-filtration. When the water goes from the settlement chamber to the
bio-chambers, does it matter
if the water flows up through the medium, or trickles down from the top?

What are the pros and cons of either method?

Thanks!

- David