IME, phosphates are as big a deal as water softness and constant pH along with other levels. Discus are hardier than most people think. As long as things are constant most of the time they will be okay and adapt. Mine for instance have been doing fine and i cant keep the pH under about 6.8. Acclimation is another big key in starting to keep discus...i take about 2-3 hours to acclimate each of my discus when i got them. I think if I were you I would keep reading but always be skeptical about what you read on the internet. And as far as the PO4 goes i might would get something like phosguard....excessive phosphates create algae....and most of the time lots of it.