start by planting the whole tank imo eco complete is the best all around substrate to start out a new planter..... i like pennywort moneywort amazonsword and java moss/fern throughout the tank theese plants all grow like weeds..... also use driftwood throughout to soften the water.... discus like still water so a sponge filter is a good way to go... in a 55 gallon you might do 2 big sponges on a air pump... german rams or the ramirezii are good tank mates in a 55 i would go with 3 discus and maybe 3-5 rams get you water around 6.8-7.0 and keep it there their diet and your water changes are the most important things