Oh okay.That seems to be an aceptible range for most cichlids.
Probably will make the PH higher. I use shells in most of my tanks BC the incoming water pH is lower where I live. After a while the shells slowly disappear then I just add more.
Make sure that the pH doesn't get too high in your tank with the crushed coral.
I got told years a go but an old man that had been keeping fish for 60+ years, that it is better to have a naturally buffered tank, he said that diseases have a much harder time coping in alkaline waters, much like the human body.
He also told me that if things are changed slowly over time things like PH dont really make a difference as the fish adapt....I didnt believe what he was saying until he showed me some of the most amazing discus that he had in pH 8.5 water....i couldnt believe they were still alive but they were massive and had the most stunning colours.

