Some of the changes that are just part of the hobby now include water testing. At least it was new to me, since I had fish 25 years ago....The first equipment even before your tank should be an
API Freshwater Master
test kit! Be sure to get the API kit, most here recommend it!. It will last through hundreds of tests, and especially if you want to keep discus or angels it is important to keep track of your water parameters.
Any fish should be researched, just as you are doing. Buy the tank to fit the fish that you want to keep. Cycle your tank before buying fish, and especially some fish like discus should be in completely cycled tanks, if there is anything you should be careful about it is that. ALSO discus need clean water, the
ammonia and
nitrite should be 0 but even as time goes along your nitrates should be down around 5. If Nitrates get up as high as 10 you need to do water changes to bring them back down. 25 % changes every day till the nitrates are where they need to be.
Some people say you should use
RO water for discus, but this should only really be necessary if you have exceptionally high
pH, or if you are breeding.
There are several discus owners on the forum, and they should join in to help you...... Good Luck with what ever you decide!