According to my research, any of the high CEC clay-based substrates, i.e. kitty litter, Safe T Sorb, Turface, or otherwise chemical absorbing materials will initially lower the KH/GH by leeching it out of the water. Eventually, the material reaches an equilibrium wherein it stops absorbing KH/GH and matches the KH/GH of the water columnů
Of course, the pay off of this initial KH withdrawal side effect, is the long term CEC benefit of the material storing nutrients for the plants to use over time.
I am currently buffering my new Safe T Sorb tank with crushed coral and will be testing to see how long it takes for the STS to stop absorbing the KH. I am considering adding baking soda to expedite this process as well.
Is the use of cat litter give the same results when it comes to KH/GH dropping?