This is bugging me. Cichlids is a VERY BROAD scope of fish. Sorry but not all cichlids are from Lake Malawi I hate to break that to some of you.
By saying most "cichlids" will do fine in that water is very incorrect.
Please, this is very easy, identify which type of cichlids your talking about. There are ones from Lake Malawi, Lake Tangyanika, Lake Victoria and a general class of West Africans. So saying African cichlid doesn't even cut it. The cichlids from the rift lakes prefer hard alakline water, while the west africans prefer soft acidic water.
Now there are South American cichlids, for a few examples, Oscars, discus,angels, Apistogrammas, Severums, peacock bass etc. Soft acidic water there as well.
Central American cichlids, Jaguars, Midas, Dovii, etc also soft acidic water but are more adaptable and hardy in general.
There are also a few other places but those are not commonly available.
Most of these fish are not compatible with each other, aggression, food requirements, or water requirements dictate this. Even the cichlids from the rift lakes are not compatible with one another, you should keep Malawis with Malawis and Tangs with Tangs period. Its very simply to classify them and call them by the correct names, not everyone knows the differences even if you do, if a newbie comes on here and looks at this, sees that and says "oh gee I can keep my oscar with a Malawi Eye biter." They won't know the difference and why they shouldn't keep them together, what your doing by grouping all of those fish together is essentially advocating that its ok to keep anything and everything together.