Unfortunately it's not that simple. In a reef system (or seawater in general), the pH is governed by the carbonate ion concentration (alkalinity) and the CO2 in the atmosphere that the system is in equilibrium with. While you can look these numbers up, they're somewhat meaningless for our purposes since most folks don't have an easy way to measure the carbon dioxide concentration in their home.
Adding kalkwasser (calcium hydroxide solution) causes a temporary bump to the pH of the water until more CO2 dissolves and brings the pH back down. That's assuming that the alkalinity of the system stays constant - i.e., the carbonate/bicarbonate ions in the water are being consumed by the calcifying animals and/or abiotic precipitation with calcium to form calcium carbonate. That's typically the case for a system with a fair number of corals that are growing, since kalkwasser is fairly dilute when it comes to calcium and alkalinity. Specifically, 1.7 grams per liter will dissolve in pure water at 20 degrees celsius, which is around 1/4 of a teaspoon of kalk powder. In contrast, the alkalinity part of a 2-part dosing solution is far, far more concentrated - typical values are around 78 grams of sodium bicarbonate per liter. Granted, some of that 1.7 g/L of calcium hydroxide that will dissolve in pure water is calcium and some of the 78 g/L of the sodium bicarbonate in the 2-part solution is sodium, but you can see that 2-part is far more concentrated.
So the bottom line here is that in a reef with growing calcifying organisms, it's quite tough to keep up with the alkalinity demand of the system solely by dosing kalkwasser to make up for evaporation, so most will dose it either by saturating the ATO water, monitoring the alkalinity and making up for the deficit with 2-part dosing, or they'll dose kalkwasser with a dosing pump at some fraction of their expected evaporation, and make up for the rest of the alkalinity demand with 2-part solution. That last method is preferred, since one doesn't have the variation in alkalinity dosing that comes with varying evaporation rates. However, in the absence of a dosing pump, and for reefers that test alkalinity of the tank water often, just using saturated kalkwasser as evaporation make-up is a decent, if more laborious, strategy.
As for the numbers I was trying to get, I currently dose 2 part to maintain alk and calc. This is working fine for me and my current pH is between 8 and 8.15 daily. I don't want to switch to kalk for maintaining alk/calc purposes or add kalk to my ATO. My plan is to use a dosing pump and an Avast Marine K1 Kalk Stirrer to add a defined amount of saturated limewater to my system throughout the day. The intent of this would be to raise my pH a bit. I know my levels are good and my corals are growing but I thought I could get my pH up a bit higher. I would leave my ATO on and it just won't need to add as much freshwater as it does today since I have another dosing pump that will be adding the saturated limewater. I know my evaporation is about 4250 ml daily so I would keep my limewater addition far below that. My 2 part dosing would be adjusted as it will have less to make up after the kalk is added. My thought is that by keeping the kalk addition constant and separate from my ATO, that alk/calc gained from that will be constant and my 2 part addition can be adjusted to keep the alk/calc in the tank stable. I know that with a higher pH my daily alk/calc demand should increase so the 2 part dosing volumes could even increase along with the addition of kalk but I don't know that yet. Here's my numbers so far and perhaps someone has some of these answers:
