Yes but you have general hardness and carbonate hardness and the two are not the same. I cannot encourage you enough to read the following links which RYANJURY kindly put on one of my posts when I was researching the same subject - I found the information invaluable, the articles will answer all your questions and stand you in good stead for understanding preferential water chemistry maintenance for African cichlids (note the comments in them made about addition of salts, which are considered elemental in helping the fish maintain their mucousy coating) ;-
Seriously phoenix, is it worth the risk ? Personally if you go that route I think you're mad, lol, but hey, its your tank . . . . I just think you can get more suitable stuff for little money. You have set up a tank for most to be jealous of, so it would be a shame to have a wipeout because you used a dubious product. Keep the pics a-comin though, cos its looking awesome.