I use a CaCO3 reactor only. My ph stays between 8.0-8.2, occasionally dipping to 7.9 I have noticed NO deleterious effects with running a lower ph; in fact, it seems like my coral growth and health has increased with the lower ph. When I was dosing KW, it was in the 8.3-8.4 range. I think a lower ph has gotten a bad rap because it's associated with other water chemistry problems, like poor gas exchange or DOM increases. Does anyone know of a problem caused by ph in this range, as opposed to problems that are indicated by ph?

Oh yeah, to answer your question, when I switched from KW to a reactor I ran both for a long time to allow the water chemistry to change gradually. There's no problem with doing this. Lot's of people run reactors 24/7 and dose KW at night.