i've changed the light to purplish white fluorescent.
i've removed the hydrometer from the tank now that i'm using a refractometer.
the two fans(1 blowing at the water, one sending air out of the cabinet) have been replaced (no photo)
i've added a diy mini denitrator that seems to be working (i'm doing 50% water change fortnightly now with nitrates rising to only 15ppm) to the outlet of the canister filter (no photo)