fine particles in tank

Nomad 'on a mission'...(I like that).

I am a little uncertain about what your problem might be but do you have playsand as a substrate? - I ask because I used some in some tanks I recently set up and there is a very fine residue of sand everywhere but this is gradually dropping to the bottom...I also witnessed the same with some 'sandy' gravel I used but this also went eventually.

I also had a residue of limescale dust (for want of a better description) when I used unfiltered water but the mains water here is so very hard and alkaline.

Other than these couple of poor suggestions I cannot be more helpful - I'm afraid...unless it's a water impurity. In any case I would suggest a few days of 25% water changing to see if that might help the problem.

Sorry for being less than helpful on this.

John

Another quick thought,
You mention cleaning your filters, if you take out the internal be sure to lift it into something like an ice cream box to collect the stuff which will inevitably drip out of it to save it going back into the tank water...here's a further point, I'm wondering if you're cleaning them too often? It's recommended that you only clean out a filter when its output is appreciably reduced - say by 30% or so but you are doing right by not cleaning both together - you could appreciably reduce to danger levels the bacteria levels if both are cleaned at the same time - and of course you would know not to rinse the filter media in fresh tap water...