Is Quartx decent for Green Texas Cichlids better or for Green Terrors, or both? Or neither. It's inert. Hmmm. I currently have a 1" layer of sand. Thinking of either covering it with 2" quartz gravel or pushing the sand to the side and add 3" quartz on most of the rest of a 75 gallon. Any ideas on gravel for these 2 cichlids?