In our initial setup, the batting provided the initial mechanical
filtering and the lava rock was intended for the biological filtering
(it might have been more successful if these were reversed). I think
lava rock could be used for either type of filtering, but it does clog
easily and we found it too difficult to clean (bad back and tendonitis
in arms require lighter filter media). The strapping tape provides both
types of filtering (lots of surface area with a indented design) and is
easier to clean, but requires rinsing more frequently than the rock.
--
Kathy B, zookeeper (OR)
3500gal pond

BenignVanilla wrote:
"zookeeper" wrote ...

... red lava rock, and ...
filter "batting." ... refilled the "rock"
barrels with strapping tape ... which is
much easier to stir and rinse ...


Forgive me if this is a naive question...is the material in the filter just
a matter of surface area? I thought the lava rocks had some filtering
property.

BV