Ok, now I think my large piece of driftwood caused the pH to drop. Does the CO2 chart still apply ? Because I doubt my DIY CO2 was sufficient enough for my 50gl but according to the chart, it's enough. It was only producing 1 bubble every 8 seconds. I just made a new mix to get 1 bubble every 3 seconds.
If the driftwood makes the chart invalid, how do I measure the CO2 level? Any equipment I should get?
My tank : 50 gl. pH 7.0 (I think it was partly caused by the driftwood, it was 7.4 before CO2 and driftwood). kH 120 ppm.