This is the boss. No calculator. Every number tonight divides in your head: the range is 10 °F, so evaporation is simply the recirculation with the decimal point moved two places; the cycles come out whole; the drift is 0.01 % and lands on a clean two figures.

One tower, five lines, and every answer feeds the next: two conductivity readings give the cycles, flow and range give the evaporation, cycles and evaporation give the bleed, the drift rate gives the drift, and the three losses together give the makeup the tower ought to be drawing. Write each line down — one slip at the top rolls all the way to the verdict.

And note what the last line asks. It does not want another flow; it wants a decision: does the metered makeup agree with the balance you built, or is water leaving this system by a door nobody has told you about? The arithmetic exists only to earn you the right to make that call. Watch for the trap the chapter has been building — a bleed calculated without the minus one comes out too large, and a balance that is too large will happily swallow a real leak and report everything as normal.

This is the survey a water treatment technician actually walks. 5★ under par here is the chapter crown. Clock in.