Thanks All For the Great feedback,
I'll start a minor GH study of the sandstone leaching CaCO3 this weekend.
A short answer to why the use of D. Buffer. The tanks that I have are gen. all amazonian (e.g., apistos. ect). Since getting back into aqaria, I have been TDY (gone) often. The D. buffer offers a stable envior (e.g., recipe) that I can let others (wife) manage while I am TDY. Asking her to do peat would be pushing it. Besides the only ones who don't seem to like it are the Rams.
Now that duty demands have lessened. I will have the time properly soften the water with peat. RO may be the next step but I'll wait to see how things go with the peat and rock removal.
Only A. borellii & A. agassizii will be bummed out about the rocks, no one else will care. Wood will have to do.