Phase 1 complete
Removed old gravel, completely emptied the tank, gave everything a good scrubbing. (the limescale was a complete b*tch to get off, and still is on the outside of the tank, but I will deal with that another day)
Got some danish quartz substrate and a black background.
Refilled the tank, treated water, let it run for 24hrs.
Re-introduced the veteran fish, got a few more from the (very helpful) LFS. Fish should appear in my signature I think.
Ordered a new lid also as the current is knackered.
Will monitor conditions and when all is good will up the stock, add some plants and wood.