Let's see if my thoughts are anywhere near accurate (though I hold little hope).
In this image one can see two switches on the left hand side, presumably for something in the system, though I cannot see leads from here. I presume if you follow them you will find what they control (or just plug everythign in and hit them and look swhat changes
)
To the right one can see a controller box which can be set (presumably) to come on at certain times of the day. Follow the lead coming from that to see what it is controlling (Tolak is most likely right with either heaters or fans).
At the top to the right of this is a tube with bioballs in it. I would guess that this is some sort of nitrate filter where a slow flow allows anoxic conditions for anaerobic bacteria to develop to convert nitrate to nitrite to ammonia to nitrogen gas. I assume there is a pump somewhere that feeds it.
Below this is a stop-cock which has an empty hose end. I woudl assume that something else needs water to run through it and a hose would lead from this to somewhere else.
At the top left you can see the stop-cock and the nitate filter. Looking at the end of the nitate filter it may be that the filter is connected tot he stop cock. The bulk of the picture is the glass sump, which has been described above by Tolak. You can see the bent white tube which is the intake for the pump mounted to the left of the sump.
The black box sitting on the right hand side of the sump looks to be some sort of trickle tower. Is there a large drain pipe which leads from the tank to over this spot? If so it is somewhere to place fitler media in the air to allow greater access to oxygen and thus larger colonies on the media.
Below this at the front is a white control box. Find the other end of the power chord to see what it controls. It looks like it might want a probe to the control something.
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Now this photo has me questioning the possibility of the black box being a trickle tower. I can't see a pipe leading to it. I can, however, see what looks like a draw where you can pull out and change something like a sponge (which perhaps sits over the media) so it may be a trickle tower after all.
There are a number of switches which you would need to follow wires from to establish their purpose and a small grey control box. The box has up, down and repeat/cycle looking buttons. I assume it is to monitor and/or control something.
I can't help much more than that I am afraid, but I hope the above helps a bit. If you want to find out more ont he control boxes, look for what is written on them and then put that in Google.