I just thought id clarify something from my last post.
I have my controller set to shut off the Co2 when the
pH in the reactor drops to 6.65.
I'm using a mix of media (aragonite, coralith c+ and Korallen-zuch ZEOMag magnesium chips). The recommendation for Coralith is
pH 6.5. But I set mine higher because I get more alkalinity than I need withouth pushing it to the limit. I find that it runs cleaner this way (less fine grit in the effluent).