Richard Holub wrote:
Hey,

Does anyone know if it is normar to find a skim layer of "black sludge" at
bottom of tank and directly on top of all filter media at end of season with
a Skippy Filter. I found approximately a 1/4 inch of sludge which did not
totaly "stink" but did have a slight hint of decomposition by anaerobic
bacteria. This was the first season I experimented with the Skippy Filter
on my "NEW" 700 gal. pond. Next year the pond will empty into a larger 4000
gal. pond with a vortex filter. The small pond will actually become a vegy
filter.



I've been using a Skippy style filter this year as well. On their
website it does mention that you will accumulate a layer of silt at the
bottom. According to them this is mineral waste from the breakdown of
bio matter. I have this as well, and will just back wash it onto the
garden. There is a slight smell to it, but nothing compared to settled
fish crap.
Like you say, there is also a layer of crud on the top of the media. I
expect that this is a thick layer of bacteria with small particles stuck
to it. Near the surface oxygen is dissolving into the water, so
bacterial growth will be greatest.
I've been very pleased with the Skippy filter this year. Previous
summers I was cleaning the oase filter every week. This summer I have
not cleaned the Skippy filter once.
I found that the oxygen levels in the pond were very low when I first
installed the new Skippy filter. I think the amount of bacteria must
have been vast, there is certainly a lot of media in the filter for it
to grow on. Some extra aeration soon fixed it.
David