On Tue, 29 Apr 2008 19:02:53 EDT, "
You should use the black mat on top as it is the coursest layer 1st.
Matala mats don't imped flow if they are too clogged. Matala mats are
very durable and easy to clean by dripping them in pond water or
washing them with a hose. Lava rock does work but it's a real pain to
deal with. I switched to matala last year and I'll never use lava rock
again.

I use open cell foam in my bio-filter, they're only cleaned once a year and
there is hardly anything on them. With a good pre-filter that is how it
should be, same with most matala pads also. I'd switch to matala right now,
and eventually will, if money was no object.

Bio-media is all about surface area, so it doesn't matter what you use for
it. Those trying this out might want to start with the least coarse
versions. ~ jan
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Zone 7a, SE Washington State
Ponds: www.jjspond.us