I know this is probable an old issue but I have some questions relating to pH measurement
Different pH scales for Seawater
National Bureau of Standards (NBS)
Salt Water Scale (SWS)
Total proton scale (T)
Free pH scale (F)
All of them have subtle differences as they each handle junctional potentials, ionic strength, HSO4 and HF . It is recommended by Millero that it is better to use SWS, T or F pH scales. If pH SWS reads 8.1, pH T reads 8.1096, pH F reads 8.217, ? equivalence for NBS
In addition calibration of of pH probes is dependant upon the salinity as well as the temperature of the calibration fluid.
My questions have to do with the available pH measurements reported in the hobby, the available measuring devices and calibration fluids given the different pH scales. What pH scale is commonly being reported in the hobby? According to Randy "These other standards need not concern aquarists: all data reported by reef aquarists employ the standard NBS system"
OK so we all are reporting NBS pH scales but this does not indicate how we calibrate our pH probes.
What calibration fluids out there use seawater buffers? What would be the difference if someone calibrated with a fresh water buffer vs sea water (high ionic strength) buffer?
Different pH scales for Seawater
National Bureau of Standards (NBS)
Salt Water Scale (SWS)
Total proton scale (T)
Free pH scale (F)
All of them have subtle differences as they each handle junctional potentials, ionic strength, HSO4 and HF . It is recommended by Millero that it is better to use SWS, T or F pH scales. If pH SWS reads 8.1, pH T reads 8.1096, pH F reads 8.217, ? equivalence for NBS
In addition calibration of of pH probes is dependant upon the salinity as well as the temperature of the calibration fluid.
My questions have to do with the available pH measurements reported in the hobby, the available measuring devices and calibration fluids given the different pH scales. What pH scale is commonly being reported in the hobby? According to Randy "These other standards need not concern aquarists: all data reported by reef aquarists employ the standard NBS system"
OK so we all are reporting NBS pH scales but this does not indicate how we calibrate our pH probes.
What calibration fluids out there use seawater buffers? What would be the difference if someone calibrated with a fresh water buffer vs sea water (high ionic strength) buffer?
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