A STABLE PH is MUCH better than trying to create an optimum PH! keep that in mind! PH fluctuations cause stress on fish !!
unless these are wild-caught specimens they are likely be perfectly happy with your water. keep up with PWCs and don't worry about the PH. the fish were probably bred in water closer to yours, anyway.
my ph in my african tank stays around 7 - 7.2 and they do great...they even breed good too, back in mid september our female greshakei released 27 fry (which are in a grow out tank now ) and i noticed on 11-18-09 that she's holding again.