Awesome i’m glad you said that because I was planning on doing a less than saturated kalk as well since this new tank is mostly frags right now. Im thinking a hybrid approach since I don’t necessarily have a PH issue like most do. i.e. just dosing the kalk as an ATO to maintain Alkalinity but hav my GHL spread that out evenly during lights out to help flatten that PH swing.Just be cautious that tanks vary a lot in CO2 exposures and, iirc, ACI used a CaCO3/CO2 reactor at the same time as the kalkwasser.
That said, I used kalkwasser for 20 years without the pH getting too high. In the early years I used less than saturated kalk and then later used full strength to replace all evaporated water. Alk never got too high in my system.