does any one have any biffers that would make my soft water a canidate for co2 injection. I got one off a cichlid forum that was 1tbs. epsom salt, 1 teaspoon baking soda and 1 teaspoon marine salt but i do not know if this makes the water co2 ready, i am not sure if this will maintain the ph i have heard crushed coal but i am not sure please help

ph=6.8-7
kh=40-80ppm
gh=75 soft