As I mentioned, pH is completely irrelevant within this context.
Sometimes you need to worry about pH, but that is in very special circumstances. In most cases the pH is measured in order to use the numerical value as a tool.
So for example, people who inject CO2 need to understand that the amount of CO2 injected is related to the amount that the pH changes over the course of the day. In that circumstance the pH is an important number because that relationship helps to diagnose problems with the injection techniques.
In other case, the pH is important number because certain agents in the water change their toxicity to fauna as a function of the water's pH. So for example, some people use heavy doses of ammonium salts as their choice for Nitrogen fertilization. When ammonia is dissolved in water there is an equilibrium phenomenon that occurs where a certain percentage of the ion exists as highly toxic ammonia (NH3) while the remainder exists as a much less toxic ammonium (NH4). At pH below 7 the less toxic NH4 is much more abundant, however, above pH 7 the NH4 converts to a greater percentage of highly toxic NH3. So this can be a source of problems if, for some reason the pH rises, but again the damage is being don by the toxic agent NH3, not by the pH.
Another typical example of this is if a fish dies undetected in the tank. if the natural pH of the water is low then as the corpse decays ammonia is released and stays as the less toxic NH4, but if the pH were above 7 then the decay would potentially have a much more serious impact on the other fish.
So, pH is something to be aware of but it's not something to be obsessive over. If you are using source water with a neutral pH, and if the tank water rises then it can only happen as a result of alkaline substances getting dissolved into the water from gravel, hardscape or filter media, or from products being added. Typically, the pH should fall because the tank normally produces acidic substances. So certainly it should be investigated as time allows but there is no difference in procedures or techniques that must be applied.
So there is nothing special to do. Large and frequent water changes are advisable when CO2 is being enriched, so the addition of liquid carbon means that you need to implement a more rigorous cleanliness policy because of the additional organic waste being produced by the plants/ A 50% weekly change is not unreasonable. Organic waste is what kills fish, not pH.
Cheers,