At a pH of 5.5 the hatch rate was approximatley 80-90%
At 6.0 50-70% was achieved
At 6.5 20-30%
and at 7.0 no eggs were hatched.
The eggs that did not hatch fungused very quickly.
The next thing they experimented was adding meth blue and airstones, but didn't change the water. The results were:
At 7.0 70-90% was achieved.
But after 3 weeks all of the fry have died which shows that an acidic pH is vital in raising the fry.
So this experiment shows how important an acidic pH is and the importance of treating for fungus. Try some experiments of your own and see what gets you the best results. I just thought this was kind of interesting and informative, so I included it.