I'll be honest, I'm kind of Confused here...
Gh (General hardness) will have the most affect on the Vibrancy of the African Cichlids Color and should be between 160-320 (clark scale)
If we are talking Gh Then 8.3 is not that high. If you multiply this factor by 17.9 Clark Scale units/ Degree your waters Gh is 148-149...
If you are talking Ph, that is not hardness at all. That is Alkalinity of your water.
Kh (Carbonate Hardness) is the measure of Carbonates and Bi-carbonates in the water that ultimately provide buffering capacity of the water. Or the ability to absorb acids to keep the Ph stable in times of ammonia spikes.
Hope this helps.