Tom Barr;22083 said:If you add the pH/KH measurements on the ADA's parameter listing, they are functionally impossible.
You can have interference from the CO2 appearing too high relative to those parameters, but never the reverse that I am aware of.
So I hold a lot of suspect for that data.
If someone can explain how someone can have a KH of 2 and pH 6.9 and a CO2 of 15ppm, I'm all ears.
Tom Barr;22106 said:ADA Aqua soil lowers pH vs the ambient levels, and if you add CO2 on top of that, and have a KH of 2 etc, your pH's should be down in the upper 5's.
Tom Barr;22124 said:Also, when you measure very low KH's, you need to be very careful with the pH measurement, the relationship changes as you get low and special probes are required for very low buffered systems.
It might be that is what is occurring.