special conditions

I have been told by many, but I would like to have further comfimation by board members. I would like to know how important it is to have exact hardness as the wild perameters to breed red bellied piranhas. or a ph of 6.8. Also would a spawn aid made by tropical science be very useful from anyone eleses past experience. It contains a special form of l lysine to trigger spawning. It says it is absorbed by the microscopic membranes in a fishes gills, and will stimulate the natural spawning cycle. Also will it be wise to mix the blackwater extract with this aid. ( i don't believe its any harm,but my girlfriend bugged me to ask) Also could anyone give me a proper dossage of blackwater extract for a 130 gallon? because I put in the suggested dossage and my water is pretty damn clear. I do not have any carbon in my filter.( which is a ehiem 2217)