I have a real problem with what I consider to be Dirt or sludge in the tank.

The substance is brown, forms in globules often very very small ones, and
builds up on all my plants. The plants are normally caked in the stuff
(normally at the top and sides where the flow is directed - but is does form
everywhere). I have resorted to hitting the plants with a net or other tool
which puts it all back in the water and hopefully the mini Eheim-filter that
I have in the tank will take it all out. The main Eheim filter is next to
useless as its not removing the dirt at all - this is just acting as a
biological filter.

Last week I made a 150L water change of a 250L tank, most of what was left
was gravel with just enough water for the fish. I made sure the debris was
distributed in the water - and then sucked it all out - replacing with new
conditioned tap water. I then cleaned the whole filter unit. In one day
only, the plants were caked in the brown stuff again. I then changed just
50L using the syphon directed onto the plants to remove it directly. The
next day, the plants were caked again. And so on......Has anyone else had
this problem and can tell me what is causing it?

I am really ****ed off! It's causing an otherwise nice'ish tank to look
grubby and unclean.

The mini-Eheim filter that is inside the tank (as I suspect this is the only
filter taking out this stuff) is caked and requires cleaning daily. It's
just a sponge and floss filter with lots of holes for debris to go through,
which I clean in tap water - its not the main biological filter.

I have a large piece of newish bogwood in the tank but this has been
happening before I put that in. My chemistry is all OK. I have a flourite
substrate which does get disturbed quite a bit by the Bristlenose Plec, and
when I plant. In the filter I have normal blue foam and a white floss at the
top, I have a mechanical filter at the base and a bag of volcanic rock for
the dear little microbes. I also have a small bag of PhosZorb in there as
well. Sometime ago I removed the carbon filter but cannot equate this
problem to that time.

I doubt whether it is the filter itself breaking down as my ammonia and
nitrite would be high and instead they are zero. Some time ago, however, I
did add some chemical called sludge buster because of this very problem - it
says it puts enzymes and microbes into the soil to help break down
(anaerobically) debris such as rotting plants and food etc. However, if this
is causing it then I would have assumed that the virtually 100% water change
would have got rid of that.

Sorry this is long.......Please help - I'm exhausted and going to chuck it
all in soon......The big "**** it!" is well past its sell by date.

Martin