The best way to manage
ph is to make sure that cal and
alk (and mg) are at the right levels. In a biocube, this can be done by with routine water changes (with a quality salt mix). If your calcium needs increase with the addition of organisms that require it (hard corals), you are probably better off using a 2 part solution, (ie B-ionic). All of the essential elements are most likely in the salt mix. I don't know much about the HBH balance block, but I bet you don't need it.
