I just setup my Co2 system too and for 2 days now its just blue.
I made my own 4dkH solution from RODI water, tested with the API kH test kit....4drops and it turns from blue to yellow which is roughly 4dkH.
Using atomizer, bubbles are really fine and set around 1bps, tank is 130L. Tank is new, still fishless cycling but with plants, not much.
Drop Checker is a standard glass ADA knockoff positioned hald way down on the opposite side of the tank from the eheim spray bar. (eheim classic 600)
I use 3 drops of API pH solution in the drop checker....blue....
ideas? I'm thinking new tank, minimal plant growth, 1bps is quite a lot right?
