SCAFFMAN wrote:

any pointers

Is this a new setup? If so, the tank is still cycling. You can expect nitrites
to start to drop in another week, assuming you have a decent bacteriological filter.

If this is an established setup, your filter mechanism is defective or
inadequate. If you have mechanical filtration, such as a wet/dry or a fluidized
bed, make sure it's functioning correctly. With a fluidized bed, check in
particular that the little pump that churns the bed up is still working. If you
have the Eheim wet/dry, make sure that water comes out in cycles as it's
supposed to. If you have an undergravel, it's probably clogged. The best thing
to do with that is to replace it. If you are using live rock, make sure the
water circulation around the rock is adequate.

George Patterson
If you torture the data long enough, eventually it will confess
to anything.