Besides the fish, filter, heater, air pump, and power head, I only have driftwood, 8 plastic plants, and 2 plastic decorations to give hiding places to the fish. *shrug*
Those cories don't do as well as other cories in higher temperatures. Keep a close eye on them, as Tolak said. Make sure you are feeding them lots, as higher temperatures mean increased metabolism.
Eco-complete carries some heavy metals/minerals, that do raise Ph. Could it be possible that these trace elements are leeching out into the tank, because they are not being used for nutrients?
I use to breed Angels about 5 years ago, from "my experience" I would never again fool around with the ph of water. I lost many fry by doing this, it is not worth it.
I just let the water be and ended up with more fry than I could handle. They will just like Discus acclimatize to your water ph just fine.
As for the fitler intake, I use to use the sponges you get with the Aqua Clear Filter, use the small ones, cut into the center of the sponge and it slides right over the intake just nicely and it easy to slip off and rinse off when it gets to dirty.