Yeah, why take the salts out of the water just to put them back in (and more) for rift lake cichlids. In fact, I have the waste from my RO go into one of my rift lake cichlid tanks. They love it.
But if you want to put your RO to work, you should do some research on the soft water apistos and west african cichlids....I mix 50:50 RO and Tap water for them.