Use the same measured loop in a small reservoir
A compact reservoir can show the effect of water loss or a small addition
quickly. Confirm the actual working volume instead of relying only on the
advertised bowl capacity. Check water level, rinse and calibrate the meter
according to its instructions, confirm the EC unit, and take a repeated
reading after the solution has circulated.
Source water contributes its own dissolved salts and buffering. Record its
EC and consider it when a familiar nutrient amount produces a different
result. If a verified reading calls for an adjustment, make one measured
change, circulate completely, allow the meter to stabilize, and remeasure.
Recalculate from that new value instead of assuming an unused remainder is
still suitable.
Keep nutrient and pH changes separate enough to observe their effects.
When repeated top-offs or corrections have made the reservoir history
unclear, a clean remix can be more informative than another patch. The
EC units guide explains the measurement, and
the reservoir guide helps separate
a top-off, dilution, and remix.