use aragonite sand when the ph fall below 8.0 ( also the ph of african cichlid pH) this stuff snaps into action and buffers bac kup to the original pH.
no, it effectively makes the ph a bit higher than from the tap. out of tap my water is 7 and with crushed coral in the african tank. my ph is now 7.8 or so.
I find Texas Holey Rock to be the best for my Africans. It raises the pH to the perfect level, keeps it consistent, and it has all sorts of holes, nooks, and crannies, that the cichlids love! I also really like the look of it. There are a lot of folks who sell it on eBay.
I use a combination of pool filter sand, texas holey rock and the rift lake buffer recipe from cichlid forum. it works quite well. pool filter sand is only ten dollars for fifty pounds