One of the easiest and most successful methods would be to use a syphon,
similar to the aquarium Python. This can be moved slowly into the muck
without disturbing large amounts, and if controlled, will not significant
increase clouding. The waste can be discharged into a large tank, allowed
to settle, and the clear water added back to the pond is desired, or the
waste with water can be used to water and fertilize the gardens or flower
beds.

--
RichToyBox
http://www.geocities.com/richtoybox/pondintro.html
Zone 7A/B Virginia
"john d hamilton" wrote in message
...
I have got about thirty goldfish in a plastic cold water storage tank
about 4 metres long 1metre deep and about one metre high.

It's full of sludgy mud at the bottom. normally they don't disturb the
mud and the water stays clear. lately though they have been rushing and
thrashing about and the tank water now just looks black.

I'm wondering what is the easiest way to clear out the mud at the bottom
of the tank. my first instinct would be to take a small bucket and keep
spooning out the sludge. but i wondering if all the sludge got really
stirred up, and this would certainly do it; whether the fish would suffer
discomfort, and whether their gills and breathing can filter out all the
mud particles, without any trouble? any suggestions to a novice most
welcome.