"Tom Wikoff" wrote in message
...
With winter in west-central Ohio on the wane, I am nearly ready to
begin
getting the pond back up and running. This will be the second full year
for the pond. It is approximately 1800 gal with a 200 gal. bio-filter.
That bio-filter has approx. 50 bags of lava rock. Last summer a young
man
at the local nursery/water garden outlet advised me to take out and
replace
the lava rock because of my complaint about string algae. I had never
heard of the need to replace this rock and find the thought of the cost of
replacing it just a bit hard to swallow. Was that sound advice? Can't
the
rock be "cleaned" instead. NOTE: I do keep small bales of barley straw
in
the both the filter and at the waterfall and treat the water with products
recommended by the people who sold me the liner, pump and fish (5 to
date).
The ratio of time I spend maintaining versus enjoying my pond does not set
well with me. Any advice would be greatly appreciated.

Sounds like Koi Poop to me. Lava rock does not filter your water. The reason
you use lava rock is that is has LOTS of surface are per rock. With all that
surface area, you have lots of room for the biological critter crew to live
and grow and filter the water for you.

I use a VF for filtration, so I can't speak to the lava rock from
experience, but it seems to me at worst, you may need to rinse your lava
rock down, and be sure that the filter box is not clogged with sediment. Of
course, rinsing the rock will kill any critters you have already built up,
so you may want to use pond water to do this.

BV.