Ann in Houston wrote:

Jan, this newsreader gets hard for me to follow the responses.

just include the relevant bits, and don't top-post...

Did you
see my explanation to Ingrid about the drain and washing out the gravel
from the
top? What do you think of that. There are a lot of ponders down here
that have this set-up, as promoted and taught by our premier pond nursery
in the
area. They've had one on their beee-yootiful display pond for about five
years, and I think they clean it at the end of each season.

I thought I saw in one of the posts that the water came _up_ through the
gravel, but I can't find it. If so, that helps, because the gravel doesn't
get so compacted as when the water flows _down_ through the gravel, but it
still isn't easy to clean. And if it's a "bog", it presumably has plants.
If it doesn't yet, it will. The problem with gravel and plants is how you
separate the gravel _from_ the plants when you're cleaning. They seem to
take great delight in working their roots around the gravel in such a way
that it is at best tedious to separate them and at worst almost impossible.

So the simplest way to clean the gravel is to dig it all out and then use a
pressure washer to clean it - totally disregarding any plant material.
Then you still have the sludge left behind. If the containment is designed
right, maybe none of it has washed into the pond and you can vacuum it up
with a shop-vac, if not you now have a lot of extra partly composted
biomass in the pond.

Gravel works, but ime most people who used it start to wish they hadn't
after, at most, a couple of seasons.
--
derek