You won?t need anything else if you run a double canister. Even with the house all closed up and me working from home Im getting my ph up to 8.52 during peak lighting. Unless of course, your skimmer is drastically under sized.
In the spring and fall I will disconnect the scrubber and crack a window in the reef room. Fresh air will fix your ph too. But in the dead of summer, cracking the window or running your air tube outside does little to nothing because of the elevated CO2 in the heat of summer. In the dead of winter if you crack a window you?re overusing your heaters which could fail and drop your temp too quickly. So in my opinion, it?s best to run the scrubber in both those extremes.