Dave, given that somebody probably paid upwards of $2,000 for that thing . . . they might object to referring to it as a "gizmo".

But your point is correct. I fought that battle many times, with pool operators who struggled to accept the idea that they were going to calibrate an $8,000 pool controller with a $25 test kit. Spectrophotometer don't suffer the same sort of inherent 'drift' troubles controls or instruments using pH, ORP, or thin film electrodes -- but they are subject to a variety of other systemic errors. All too often, equipment operators fail to validate them, and then use them to generate useless or even dangerous results.

But, properly calibrated, such systems are capable of producing results almost as good as old-style buret titrations!