I started this in the Dolomite thread, but I think it deserves it own.
I recently started up a tank with a base of laterite and a some Knop's, and it seems to be working greatly. When I was setting up my tank I was researching buffering media, and I figured why not use something I already have. I had some leftover from my Ca reactor, and it is specifically used as a buffering agent. So, I gave it shot. So far no problems. My base is just laterite, Knops, and then gravel.
I have been closely monitoring all levels and they seem to be fine.
Also, for the Ferts guru's. Do you see any problems?
Maybe I found something for people who keep reef tanks and planted tanks to use as a substrate base. Especially because most use RO/DI water and truly need a buffer.