Too bad about the Arabesque design getting dropped. I like the idea, but perhaps it is more exotic from where I'm sitting and a limestone fascia is exotic from your "stakeholders" perspective.
It looks like there has been some breakdown in the concrete in some areas, but perhaps that is part of the renovation work? You really should look at a 10% silica fume portland mix to parge (skim coat) the walls.
How did the epoxy hold up? The crystallizing agents I recommended earlier will repair any leaks in the cement.
The steel support above the glass also appears to have rusted. This would be a good opportunity to delete this detail or at least replace with stainless steel. The flanges that hold the steel tubing also appear to have corroded. These too should be stainless steel or at least epoxy with a polyurethane top coat.
Are you replacing the glass or just resealing it? The silicone gasket should be at least 1" thick for a tank of that size.
I can see that the sand was causing problems by the black colour of hydrogen sulphide. If you add a substrate this time around, use calcium carbonate or aragonite.
For a project that big, you should be using 100 or 300w multi chip LEDs. Strips will not illuminate efficiently or cover much area. Your GHL Profilux controller can simulate the lunar cycle and dim tho flights to the desired mood.
You can buy or rent a gunite machine to cement the rocks in place and add realistic texture. Drilling large rocks is not difficult with a diamond hole saw, and they are available in any length. You can drill 1" holes to use PVC pipe for a support network. Carved styrofoam is a cheaper option for the base and it offers more flexibility in design. You can coat it with cement or epoxy & sand. You can buy aragonite sand for $150/tonne from the Caribbean.
Make sure you are using porous limestone and not heavy granite for your rock formation. It should be easy to acquire from areas where the port has been dredged for boat passage and new docks.