Can't really say why the tables are sometimes so far off but I do read about it lots of times. Maybe approach from a different way?
I started CO2 with the main concern on my fish. Kind of deal where if the plants made it fine but the fish came first. I also have a controller so I started with testing my PH and then very slowly worked my controller down over a few weeks. At some point, my fish began to act funny and I moved the PH up just a bit. In my case, it turned out to be almost an even 1.0 down from my normal PH (7.8 & 6.8) Just for a bit of slack, I now run 7.0 and fish and plants seem happy. I run African cichlids and was not really expecting to get that low for them to be happy but they keep on breeding!
I started CO2 with the main concern on my fish. Kind of deal where if the plants made it fine but the fish came first. I also have a controller so I started with testing my PH and then very slowly worked my controller down over a few weeks. At some point, my fish began to act funny and I moved the PH up just a bit. In my case, it turned out to be almost an even 1.0 down from my normal PH (7.8 & 6.8) Just for a bit of slack, I now run 7.0 and fish and plants seem happy. I run African cichlids and was not really expecting to get that low for them to be happy but they keep on breeding!