What does pool photometer mean in practice?
Depending on its programme and reagents, it measures pH, chlorine, bromine, alkalinity and other parameters more objectively than visual comparison.
When does it matter?
Bubbles, fingerprints, scratches, missing zeroing, wrong reagent and over-range samples bias the result.
Which solutions are related to it?
Rinse the cell with sample, wipe and orient it consistently, run a blank and periodically check with a control solution.