-Should i do a 30 or a 50% water change weekly?
50 or MORE. I do at least 80% weekly.
-What kind of mechanical filter should i use(trying to stay away from canisters and sumps) I use a HOB in addition to sponge filters...it realy doesn't matter.
-Should i also add some artificial plants to the tank so they will have places to hide?
I have driftwood, plants and some small rock formations...the theory is, the more places they have to hide, the more secure they feel in the open. It seems to work.
-How often should i feed my Discus
(will have a variety of different strains and sizes)
My breeder stresses AT LEAST twice a day and three if possible. Personally, I feed twice liberally per day, and then once a week, I feed only once.
The young ones (under a year) I feed as often as I think about it...up to 4 times a day, just not HUGE amounts like I feed the older ones.
-Do you have any tips on keeping Discus
Large water changes, then more large water changes.
-What are the main diseases except Hexamita that affect Discus
That one I do not know. I DO know that they start turning black in consistently bad water conditions, but I don't know if it has a name...
Hope this helps!