This is a new one for me. I just checked my pH and it has gone from being a steady 8.2 since the start of my tank (1.5 years) to 8.5. My alk is 9 and my Ca is 420. The weather has been nice so the windows are open, maybe this is the cause. Any reason to be concerned. I remember reading this some important relationships between Ca, Alk and pH. I think it was in one of Randy's articles.
