FYI decomposing organics in new substrate can cause the release of CO2 and mess with your DC. I've experienced this first hand, my DC was always yellow. It seemed to stop after a few weeks.Substrate and water parameters will make no difference, as drop checkers work from the exchange of gases in a pocket of air between the water and the solution. What colour is the fresh bromo blue when added to the 4dKH solution? If it is a deep blue, then it is working fine.
If the drop checker turns green and stays green once inside the tank, the level of CO2 in the water isn't dropping quickly enough for the DC solution to react before you start injecting CO2 the next day.
I am a bit confused about pH dkH tables.It is the pH of actual tank water,isn't it?mines always green in the morning and yellow when lights are on. if plants are healthy and fish arnt gasping at any point, I wouldn't worry about it. as already mentioned use a ph pen/meter and make a ph profile this should tell you all you need to know
The drop checker is providing an indication of CO2 levels in the water, regardless of where it is coming from. I responded the way I did because I assumed you were referring to the potential buffering or softening capacity of certain substrates.FYI decomposing organics in new substrate can cause the release of CO2 and mess with your DC. I've experienced this first hand, my DC was always yellow. It seemed to stop after a few weeks.
the best advice at the momentKadir, if your plants are healthy and fish are happy, you've nothing to worry about