"~ jan" wrote in message
...
On Tue, 3 Jul 2007 14:57:25 CST, "George"
wrote:
The sludge I was referring to occurs on the bottom of
the pond where detritus settles out and can become anoxic in areas with
little or no water flow, especially where there are rocks piled up.
the pH, over time will begin to rise because of the
build up of sludge on the bottom. That's my understanding of what
happens.
On Wed, 4 Jul 2007 11:33:21 CST, wrote:

that sludge is anaerobic, and anaerobic digestion releases hydrogen
sulfide H2S, which when combined with water is sulfuric acid H2SO4 ...
an acid. Nitrogen is released, bubbles rise to the surface and leave
the pond.

I would like somebody to do an experiment!!!! Ingrid

I was thinking similar. My understanding is when one has a build of
sludge
one is heading for a pH crash, where it goes acidic. I suppose that could
be because the breaking down of sludge is also using up the buffering/KH.
~ jan
------------
Zone 7a, SE Washington State
Ponds: www.jjspond.us

Sludge build up increases the total organic carbon and decreases the
dissolved oxygen in the water. Yes it does release H2S, but only when it
goes anoxic (otherwise, it can't support the anaerobic bacteria that
produces that gas). However, the acidifying effect of H2S production is
usually overcome by the changes in TOCs and DO, as well as gas exchange
into the atmosphere, which is where the H2S will end up if circulation and
pond surface area is adequate. Buffers can be depleted which can lower the
pH, but if you have a lot of carbonate rock in your pond (like I do) or
have a concrete pond, a significant reduction in buffering capacity is not
likely to occur. One thing is clear, and that is that a high pH is harmful
to both the fish and the plants in the long run, and should not be ignored.
So keeping sludge to a minimum and maintaining good water flow and
oxygenation is essential to a healthy pond.

George