EVIDENCE
Methods
This edition publishes source-based notes. The other evidence labels stay unused until a record exists.
A claim should carry enough context to check it. We distinguish what a document says, what a calculation assumes, and what an experiment actually measured.
What is the difference between a source note and an original measurement?
A source-based note explains identified publications and their limits. A calculated example is arithmetic with stated assumptions and no experiment. An external measurement belongs to its original author, sample and conditions. An original measurement would be our own documented experiment, and none is included on these pages. This edition publishes only source-based notes.
| Label | Meaning |
|---|---|
| Source-based note | Our explanation of identified publications and their limits |
| Calculated example | Arithmetic with stated assumptions; no experiment implied |
| External measurement | A result attributed to its original author, sample and conditions |
| Original measurement | Our own documented experiment; none is included on these pages |
What would an original nutrient test have to include?
Calling a result an original measurement requires the instrument, the probe, the recipe or sample, the calibration standards with lot and temperature, the raw repeats, and a sentence that states the limits. As-found readings stay separate from any later adjustment. A displayed TDS ppm stays in its own column with its factor. This edition has not published that record.
Pool water, aquarium water and food samples are outside this edition. They do not share this nutrient-solution method, and this edition publishes no performance pages for them. Related shops that sell into those scenes are named only on the disclosure page.
What do the blank records contain?
The downloads contain column headings and one empty row. They are documentation aids, not test procedures and not certificates. Repeatability, calibration and a reservoir log are separate files so those observations are not mixed. If a later page discusses scatter, ten repeats is the working minimum set for that record. This edition has not published such a series.
Repeatability CSV ↓ Calibration log ↓ Reservoir log ↓
Which sources do these notes cite, and how?
These notes cite Science in Hydroponics for a fifty-solution EC experiment, a same-EC comparison, the 500, 600 and 700 scales, and the immersion boundary. They cite WHO and the Drinking Water Inspectorate for the limit that TDS is not a drinking-water safety decision, and Thermo Fisher’s pH handbook for what ATC corrects. Retail listings can name a model. They do not establish a handbook specification.
- Science in Hydroponics, predicting EC ↗
- WHO, total dissolved solids ↗
- Drinking Water Inspectorate ↗
- Thermo Fisher pH handbook ↗
Who reviews these notes, and what does the date mean?
These notes carry the WaterMeasure byline. That byline is not a review by a named chemist or an accredited laboratory. The date on a page marks a substantive review of the text or sources. It does not mean a solution was measured that day. A named reviewer is credited only for work they actually reviewed, and no such credit appears on these pages.
Corrections identify the changed claim and its basis. Corrections with the page, passage and source.
Who owns the related retail shops?
The operator also owns instrument retail sites. A related retail link is commercial context, not independent evidence. hmdigitalp.co.uk and smartquali.co.uk may be linked beside that relationship. foundpage.co.uk, waterquali.co.uk and yinmik.co.uk are named only on the disclosure page. Ownership never substitutes for a handbook check or a measurement.
Policy text reviewed 23 September 2026. Commercial disclosure.