Because hydroponic nutrient
mixtures are usually composed completely of salts, their approximate
concentrations can be determined via their conductivity values. However,
and as discussed above, because each individual nutrient has its own (i.e.
different) specific conductivity value, and since, in a hydroponic system
the concentration ratios between the nutrients are continuously changing,
conductivity readings need careful interpretation. Only significant
differences in day to day conductivity values may have any significance.
Nevertheless, despite these
difficulties, when intelligently used, conductivity values are a valuable
monitoring aid.
Further, the above evidence clearly demonstrates that it is far preferable
to quote conductivity values rather than TDS to monitor changes in
hydroponic nutrient concentrations. Converting conductivity values to TDS
is unnecessary and prone to large interpretation errors.
