Listen.........What's on top of the lava rock? If it's just plain lava rock
and no other type of rock on top, then the clogged lava rock will float to
the top eventually being replaced with less unclogged, if its an up-flow
type.....You can even get it stirred up a bit and net out the floating
pieces....But 50 bags for 1800 gal???????? That's almost a whole pallet of
the stuff.....At $3.83 a bag.....Let it go......Don't replace it. Pull out
the bottom most clogged stuff, IF their is a flow problem....If not, let it
alone....The bacteria will re-generate and help get through the seasonal
algae bloom....BTW, string algae grows in a 1 gallon pot sitting in the sun
by itself if the conditions are right, so the lava rock has nothing to do
with it...What chemicals are you "adding per instruction"? What kind of
barley straw are you using? The type made for "ponds" or say, a bale bought
at a feed store? Careful with this answer.......You need to get a high
school biology book and read it...Everything in your pond is in that
book....Such a simple thing..Instead of worrying about formulas, etc, worry
about how cold the beer is, or if the 5 visible planets can be seen again
tonight....Ma Nature will take care of your pond....Someone in here years
ago said "Benevolent neglect is the key to having a clear pond"....So
true...Relax man relax....Keep the NG up to date with what you do...I have
done what you are about to with one of my test ponds....I wanna match notes
so get a notebook on start recording...BTW I use NO chemicals...Just nature
is present....




"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.