I have learned that I can keep Nitrate at 5 by doing twice-weekly water changes of 55 gallons. That's what I've been doing. The Discus eat four, sometimes five, times per day, a mix of Freshwater Frenzy soaked in Seachem Nourish, Hikari Micro Wafers, and at night, Shrimp pellets. Temp is now at 81. There is no aggression toward them from any fish. I've watched while lights are on, while lights are out, and all night long (just finished a week of Finals -- I was up). They continue to be active in the entire tank and graze on algae all day. As you can see from the photos I showed, this is a tank in which no dead or dying leaves are on the plants, with spotless substrate, due to my loaches and cories, and one with excellent water quality and stable water chemistry.
I have done everything I have been told, as I said earlier. The only thing I didn't do was move them to a little bare-bottom tank where they would have likely been miserable, possibly turned aggressive toward one another because of the close quarters, and lacked the algae they enjoy grazing on so much, and have to put up with me doing daily water changes because the volume of the tank would be so small as to lead to higher nitrate concentration in the water. Water quality is pristine. The tank is warm.
I know that everyone has opinions on how to keep fish. But, seriously, do you think that no one is ever going to test a new theory? We're just supposed to keep doing it the same way we always have, even though the hobby is progressing and the fish are being captive bred?
I understand if some people don't agree with me. But that's really no reason to argue with every single person who posts on this thread with good results that's trying the same thing I am. I can look back and see your posts -- I know how you feel. But, it's good to hear that some folks are seeing success with this. If they exist, then I can do it.