wrote in message
the problem with gravel as a mechanical filter is how do you clean it?

I fixed a bottom drain in the back, and I disconnect the pump and just wash
out the gravel from the top with a hose. I just hate to break down a d__n
filter container and remove the pads and wash off the muck, muddying up the
ground in the area and generally making a big mess of things. Also, never,
in nearly ten years of ponding have I had a filter that didn't have to be
cleaned once a week except in the dead of winter. Our pond season here is
from about March to the end of November, and it is nice that way, but it
makes for many, many weeks of filter break-down and mucking out. Where this
bog sits, is on a rock-paved patio with drains right behind the pipe where
the algea will wash out. I get no mud, and there are no gunky pads to wash.
I have been wanting one of these for three or four years and couldn't
convince DH that it would sufficiently filter the pond. The wearing-out of
the canisters gave me the opportunity to push for a change. Then, I got the
literature from Nelson's Water Gardens here in our area to back me up, and
just went out and bought the stuff to do it and forced his hand.

when algae dies it just breaks down putting organic wastes back into the
system. the
biofilter needs to handle the wastes, but eventually the nitrates must be
dealt with.
only plants and anaerobic bacteria get rid of nitrates., plants use em to
build
plant mass, anaerobic bacteria leach toxins back into the water as they
get rid of
the nitrates.

I do have plants in it. I have taro and iris, and I will have some
horsetail and eventually some impatiens and whatever else I can manage. The
algae I was concerned about was just what was removed at first, as the green
water got cleaned out. As soon as we move the fish, find the leak and fix
it, remove a good half of the fish load and add some lilies, I really think
the issue of heavy algea build-up will be moot.

when there is a big algae die off the best is to catch it in a filter and
remove the
organics from the system. then let the plants in a veggie filter remove
the wastes
into plant tissue that is not rotting and going back into the system.
Ingrid

Well, I can see your point about that, and I may be able to rig some kind of
holding tank with plants in it between the bog and the main pond. That
could be very attractive, as well. But, if we avoid a "big algea die-off"
with the reduced fish load and more plants in the pond, will it still be
necessary? It would look very nice, but it will really require some
finagling.