I use dragon stone as it is inert and will not effect the hardness. Also i only see the use of ro water beneficial because I will be using seachem equilibrium to re-mineralize the water. I have a ph of about 7.8 out of the tap and in the tank I have a ph of about 6.0-6.5 due to the aqua soils buffering capacity.
My apologies,After reading your post started on 10-7-16 regarding the rock's you purchased and their affect on GH and considering your Aquasoil that was lowering PH,I responded perhaps confused as it often get's when adjusting water .
My tap water is pH 7.6 to 7.8 after off gassing, and 12 dgh but over time the water drift's down to around 7.4 without CO2 injection.
Have managed to keep wide range of freshwater fishes.
Depending on what the aquasoil does in your tank and sudden change to the water from hard tapwater, or possibly calceous rock,will bout have to have water pre-mixed for water changes.
Or,do away with the stones if they do indeed as was mentioned in the post last month ,raise the GH.
Again,my apologies if a different rock for aquascaping was chosen or report's that the stones would raise the GH too high ,was premature.
Much easier most times to just use fishes that will thrive with the tap water you have, unless prepared to mix/store water for water changes.
More critical in larger tanks where more water must be prepared.