need to raise general hardness(GH) and keep pH same

jdm free

i need to raise GH but keep the pH the same. at the LFS i think they screwed me over by giving me KH/pH plus to raise the hardness but my pH is now at ~8 and KH and GH are at 5*dH. i want it to be closer to 10*dH. what can i use, ive been reading but everything i read highers pH as well and nothing really for GH.

FordMan

limestone in the filter or a bag on coral sand

jdm free

so would i just put a piece of limestone in the filter. its a bio wheel 200

Pasfur

This is a very complicated question. In order to answer properly I really have to ask WHY?

Are you experiencing pH fluctuations that you are trying to prevent? Are you testing General Hardness or Carbonate Hardness? What type of buffer did you use and what are the ingredients? Do you use tap water or RO water? Have you tested the tap water as well?