I would not worry about the green water to much if you are doing floating plants. Like in a pond it takes some patience but the plants will catch up and filter out the green. A clam or two would also help the algae in the water as well.
Yup, that's true. With floating plants the lighting level in the water column will be much lower. I also read the very interesting thread about the algae scrubbers. Because I've got enough light anyway it might be interesting to try such a set up. Nitrate levels can sometimes be quite high in discus tanks. Much food going in!
some pictures filling the tank. Roll out the hose and let it run for a few hours.
Starting to fill the tank.
And it's full. I left the tank standing with water for more than a week.
No leaks! phew!

The water company loves me!
Parallel with building the tank, I also started with the background.
When work on the tank couldn't go further (epoxy drying, waiting for the glass), I could get on with the background.
For the background I would like to create the illusion of a river bank.
Whereby at lower level you could see light brown rock and above that a thicker black layer of humus. Something like this, but then a bit different.

I've made some backgrounds already and it has been my experience that the darker backgrounds give a better illusion of depth. So it will be much black humus and less red/orange rock for the background.
Furthermore I wanted to integrate into the background design :
* Some large overhangs in the corners for the discus fish to hide under.
Also the corners become almost invisible, giving the illusion of greater
depth.
* Some caves for dwarf cichlids
*Create some kind of small streams into the tank to give marbled
hatchetfish or other flow loving fishes a good current to swim in.
*Create some safe areas where young fish can hide without bigger fishes
being able to catch them. (By creating some small pools in the
overhangs with narrow acces. Small fish can get in, bigger fish can't)
* The small pools above the overhangs can also be used to grow plants
that demand a lot of light
* Filtering, space between the tank wall and the background will be used
for placing heating coil, pumps and filter medium (kaldness) of the tank.
So I bought some styrofoam sheets and polyurethane sheets and loaded them in the little car. Didn't fit, but fortunately space is unrestricted in the vertical direction
In the garage I screwed together some 18 mm plywood with the same dimensions as the tank.
Ready to glue together the styrofoam with silicone. And start shaping.