Hemio is right on the water conditioning topic. Malaysian are blessed with good quality water thus we are spared the trouble of actually conditioning the water to the specific requirements of discus. Just pre-treat the water and use it. I age my water for about 12 hours.In my many years of keeping and breeding, I have not had trouble with just using normal tap-water. Discus will flourish and breed even in that spectrum of water specs.
Just another point to note, I'm not so sure bout using corals. They actually hardens the water considerably though they boost the ph and keep ammonia at bay. Discus will tend to act skittish in hard water. That is my personal experience.