Originally Posted by
D'bunk
Your water changes are just fine. The number one reason people have to do frequent water change is because they overstock and overfeed. Nitrate are almost never an issue and certainly won't be with your current schedule. Stuffing beef heart into warm water is simply creating a bacteria playground. People end up with sick fish and blame it on nitrate not realizing it's not the nitrate that's important when they change the water, it's the reduction in the bacteria level from all the rotting food that's key.
In any case, your tank is perfect for a small group of discus. I wouldn't put more than 6 discus in there given your other fish. Feed them twice a day. It's more than enough. I'd also stay away from frozen foods. Not much different than raw beef. Almost any major brand of processed dry food is healthier anyway. It is a good idea to mix brands, types, etc. Freeze dried worms and shrimp make a nice change up.