Tahitian moon has no nutrients so it does not help plant growth at all. Its also inert and doesn't change PH levels. Alot of cichlid tanks that I've seen have sand (crushed coral) in them. The cichlids will do their own decorating but it usually doesn't cause any problems as the sand will settle quickly. The only potential problem is the filture intake, you'll want to cover it with some filter floss to prevent sand from entering and messing up your filter's impeller.