I have a 450 litre planted discus tank with daltons propagating sand as the substrate. The sand is virtually totally covered with ground cover. I have driftwood in there as well. Six discus 12+cm, 5 fancy plecs, 20+ rummynose, 15+ sterbai cories, 10 harlequins, 3 SAE and a couple of young BN and hatchets. Temp is set at 28, tanks has been sitting at 30-32 for weeks and I only had trouble when it hit 33 one day. The discus came up to the top of the tank for air. I run a big filter (fx5) on the tank and an airline. Lighting 2T5HO lights and two custom made T8 lights. I vacuum (as much as I can which isn't a lot) every 3-5 days and waterchange 50% at this time, using warm water from the tap set at tank temp and add waterconditioner to the tank when I first turn the hose on. The whole process takes 1-1 1/2 hours each time. The tank is well established (has been set up for over 2 years). Feed bloodworms, tetra bits, mozzy lavae, algae wafers, courgette. Dose with flourish every 3-4 days and flourish excel only when needed. I medicate with prazi as part of my routine every 5-6 months. pH is 6 which is as low as my test kit goes. Water comes out the tap at 7.4.
The only fish I have struggled with in here has been neons and cardinals and while they exist they only last 12-14 months due mostly I think to the temperature of the tank.
The discus spawn regularly (wrigglers go up the filter) and the cories lay eggs every few weeks. The rummynose have also spawned once in the tank.
If you want to go the planted tank way my advice would be to get bigger discus to start with. Smaller discus need daily water changes or their growth may be stunted. They also need clean tanks and its a lot harder to keep the tank clean if its planted.