Before you get these fish, you need to sort out your water parameters. First, what is the GH (general hardness), KH (carbonate hardness or Alkalinity) and pH of your source water (tapwater presumably)? These numbers will tell us what if any mineral salts may be needed.
Second, if you do have to mix water, remember this is going to be necessary for every water change. The water must be prepared outside the aquarium housing the fish, then added when it has identical parameters. As someone who has done this, it is not as easy as it sounds. It gets expensive, and has risks. I mention all this because it appears you are relatively new to the hobby. Even with my 30 years experience I would cautiously go down this road.
Third, a 30g tank is too small for rift lake cichlids except for shell dwellers. I believe this was noted in another thread.
If you have very soft or soft water, neotropical cichlids (South and Central American) would be better fits so far as water is concerned.