Baking soda can be used to raise your KH
. What is your KH
and do you really need to raise it? Be very careful not to raise it too quickly -- it can stress the fish. Never dump baking soda right into the tank. Mix it into another container of water and use that water for your water changes, if necessary. When I did some experimenting with baking soda in a jug of water, I don't remember how much baking soda I used, but it was just a small amount, and it raised the KH
quite a bit.