I must mention about this more.
I hate the PH/KH
chart for calculating co2
and think its relied on too often.
My PH is currently 7.3 and KH
14 which according to the chart is 20ppm co2
However my drop checker is a yellow/green colour using 4dkh solution accurate to 0.01ppm.
This would indicate 30-35ppm co2
and further more my aquarium water degassed is 8.3ph so I am getting a whole 1 point drop in ph which is about right for 30ppm co2
Problem with relationship chart is it does not account for any buffers in water for KH
or phosphate and this is even more apparent when you are EI dosing and adding 2-3ppm P04 on a weekly basis.