ammonia must always stay at zero, nitrites at zero, and nitrates/ phosphates should be undetectable-temp at 88°F, and pH isn't a big deal
bear in mind that discus get BIG (dinner plate size, or close, heh) and as they mature, become less group social, and more pair bonding/territorial, as a general rule-they should really be kept in no smaller than a 75 gallon tank, if you want to truly enjoy their character
feed them a high quailty pellet (dainichi roxz!) supplemented with both bloodworms, blackworms, and mozzy larvae-they eat slowly, over a very long time period-if their forehead area becomes lightly concave on either side, you're starving them
when you go look for some-watch 'em poop-their turds should not be long, stringy, or any color other than a solid brown, and the stool should appear relatively solid and thick, breaking off around 1/3 inch length at the most-if other, that indicates either a wonky diet, or internal parasites
i'd treat them regardless for worms, as most have them-praziquantel is spot on for that (marketed under the name 'prazipro' by hikari).