I have had 6 african butterflys over the years and none of them ever died to sickness. or the wrong ph. And I have pretty hard water. Ushally around 7.5 to 8 in ph. Sadly they to jump out of tanks very often. it seem's no matter how small the gap in the lid they find a way through it. Good luck though there very cool fish and lots of fun But dont get 2 get one or 3 or more. floating plans help to calm there tempers too. In my experince they don't like surface dwelling fish. Best of luck.
Delhezi B