The water chemistry is fine, having a little trouple buffering the ph but am slowly getting it under control. But any advise on keeping the ph at around 7.0 would be greatly appreciated, it is currently around 6.0 to 6.5 and trying to find ways to keep it high enough. The reason for feeding beef heart is it is very clean and the fish are in an undersized tank for there eating habits. I haven't heard of PH burn before, can you please explain this in more detail, I would love to know!