Super high pH, don't know why

[Delphinus]

Thanks - actually I don't have any coral based substrate or limestone in there as Calgary water is already pretty hard to begin with.

I did figure out it's the source water to blame (lot of limestone upstream).

I ended up cranking the CO2 (2 bubbles per second or thereabouts) to get pH down a bit. The end result is this (funny you brought this thread back to life 5 minutes after I took this picture and was thinking of uploading it):