Please explain to me everything about adding and dosing suppliments and how to do this

[Randy Holmes-Farley Verified Community Expert]

So, I was assuming that the pCO2 would remain fairly constant during the dosing spike, but I gather from your two previous posts here that, in fact, the substance being dosed may have a significant effect on the pCO2 in the water, making my assumption false. Am I on the right track here?

Right. Spike in hydroxide (such as limewater) or to a smaller extent, carbonate, and the total CO2 present doesn't change for some period, but there's a big swing of CO2 to HCO3- to CO3--. So the effective pCO2 goes way down.