Unless you remove the fish first, I believe that this would be a very bad
idea. The hydrogen sulfide that is produced in the anaerobic conditions is
very toxic. Blasting it loose would free the hydrogen sulfide and kill all
the fish. The main group of installers of gravel bottom ponds have a
requirement that the pond be drained, power washed and restarted each year
to work properly. No rocks makes it easy to keep the mulm from building up
thick enough to cause the anaerobic breakdown, and it therefore safer for
the fish.
--
RichToyBox
http://www.geocities.com/richtoybox/pondintro.html

"David" wrote in message
...
On Tue, 02 Aug 2005 14:47:39 -0700, JGW wrote:

I have read that it's impossible to keep the
pond clean with rocks on the bottom, and that they can trap hydrogen
sulfide gas.

What are your thoughts?

I have been considering this as one possible solution: Has anyone
tried, or know of anyone who has tried using a *well-controlled*
water-blast wand, (using pressurized pond water), to roil up any
settled mulm around the rocks, which would then be pulled out through
the bottom drain? This would only be done perhaps once or twice a
year, and would of course be expected to temporarily load up the
filters, etc. But it seems that this might be one way to permit one
to rock the bottom. Any opinions, thoughts?