Planted Tank Guru
Join Date: Jul 2010
Location: British Columbia, Canada
Yes, you can use soil and a gravel cap, but it's far from ideal for keeping discus because it's quite difficult to maintain an above average tank cleansing routine, and to maintain the high quality water conditions that discus need - particularly if you're new to keeping discus. Most experienced discus-keepers would recommend a barebottom tank for discus newbies to get started, or if you want a planted tank - keep it simple & go with pool filter sand, and use root tab ferts in a low-tech environment, as I do.
Among others, plants that do well in that type of situation, and at the higher discus temps, are Jumbo Vals or Grasses, all types of Echinodorus (amazon swords), Anubias, Java Ferns, Hygrophilas, Crypts, Rotalas, Bacopas, Ludwigias, Lotuses (nymphaea), Crinums, Sags, &bsome others.
Hope this helps.