On the top off strategy, that can work, but be aware it means your Kalk dosing is not really under control. A cool, humid, day you would have a bit of Kalk added. A hot, dry, day, maybe even with a fan running over the tank to cool it, you'd have a much higher amount of Kalk being added. Additionally top off usually surges during the day when it's hotter, versus at night when you actually want the pH boost.
That's in regards to just adding Kalk to your top off. If instead you use a doser to dose a bunch of Kalk at night, equivalent to your daily top off needs, that keeps it consistent but means you still need a separate ATO and you're adding salinity variation.
I say this as someone who did that ATO route initially and had coral losses during a heat spike. I now dose most of my kalk at night, and let my ATO do its things otherwise.