As long as your water quality is consistant you can keep domestic discus in just about anything. I know some very successful people that keep their domestics in pH 7.5+ and hard water. Wilds will be a bit more finicky, but even then, once you get them used to it they'll be happy in any water as long as it's consistant. Water Changes 2x/week are usually sufficient for people not trying to grow super huge competition fish.
If you like that discus go for it! They can be very rewarding. Something to keep in mind, if you ever want to add more, you'll need to add 4 at once. They don't do as well in groups of 4 or less, unless they're alone. The whole schooling and cichlid dominance behavior thing can take its toll on the least of the group.
Best,
Phil