I remind all members to keep the conversation on the tank at hand, and refrain from slinging insults at one another.
On the topic of buffering a tank with African cichlid substrate:
As Colin pointed out, and Byron agreed, African cichlid substrate is almost always made of a material like calcium carbonate or similar material, which is selected for that substrate to be of fine granular size (as African cichlids generally churn up the substrate with their mouths a general behavior, which gives rise to the genus name for many of the species in the aquarium trade under the generic title African cichlid - geophagus), and one that will slowly dissolve calcium and other alkali metals into the water column, as well as carbonates... (the lower the pH the faster the rate of this reaction).
On the flip side, as pov stated, aquarists can work against this reaction to keep the pH lower through a variety of means, though generally speaking, that is a losing proposition. As pointed out above, as soon as the pH is lowered by this counter measure, the reaction to that change is that the calcium carbonate will just dissolve even faster to make up for this change. Hence why it is a 'buffer'... the calcium carbonate in the substrate will work to maintain a constant pH of around 8.2 or so... if it starts to drop below that, the reaction will increase to correct it back to that same pH level.
And from the OP's point of view, that would be extremely counter productive, because the substrate itself would actually be dissolving away in the process... and would eventually run out and be gone. The attractiveness of the substrate being the only reason for adding it to the tank at all now, as they have decided against the African cichlid stocking plan.
Ultimately, the addition of this substrate (African cichlid substrate) would cause more problems than it would prevent given the current stocking plan, and I am glad to see that the OP has decided to go with an alternative substrate that is more inline with their current fish stock.
