Empty CO2 tank
Well, the CO2 tank is empty again.
I changed to my other today, good to have a spare one.
I checked my measurement log for time of tank emptiness, that was quite fun because you could see what happens.
I placed some figures on the graph to describe what happens (the purple line is CO2 on / off):
1: Tank empty somewhere here.
2: Light goes on and the CO2 uptake accelerates.
3: Light goes off.
4: Water change, this pushes the pH to ~7.5 but normally it only goes as far as 6.8 if the CO2 system is running normal.
