I don't know about fancy set up like yours but it's a myth that discus don't like a strong current. Mine play in the incoming water when I do a WC. I would give them a place with a current and a larger place where the water is more calm. Keep the tank BB with maybe a large piece of driftwood with java fern and Anubis glued to it plus lots of large WC with aged water and your Discus will be happy.