Just recently I put in one cu ft of corosex in a 1.5 cu ft tank and raised the ph +2 however it made the water go from soft to about 3 gpg hard. That is one way, you could also use calcite as well or mix the two though you will want to use a backwash filter because they will harden like concrete. This system is the least troublesome, you plug and play and do not need to do anything until the media no longer affects the water, then you simply replace it. Chlorine will also raise ph as well as disinfect the water if you feel you need to do that and to my knowledge will not raise the hardness. You can use the same chem feeder or use a canister that you put tablets in.