Overview of the Phosphate (Low Range) Hanna checker
The Hanna HI-713 is a small handheld colorimeter that measures phosphate in water. A chemical reagent is added to a water sample in a 10mL glass sample vial. In the presence of phosphate the sample changes to a blue colour, by measuring the degree of colour change the colorimeter can determine the concentration of phosphate in the sample.
Suitability for monitoring purposes
| Monitoring purpose category | Likely Tier(s) | Suitability |
| Engagement: Education and raising awareness | 0-1 | ✓ |
| Surveillance: Ecosystem health screening | 1 (2) | ✓✓ |
| Investigation: Helping to target further action | 2 (3) | ✓✓ |
| Evaluation: Assessing the impact of actions | 2 (3) | ✓✓ |
Details: The low-range device measures phosphate in the range of 0 – 2.50 ppm as PO4. Accuracy is stated as ‘+/- 0.04 ppm +/- 4% of reading (at 25°C).
Data System: N/A. Results are not stored on the device, so they must be recorded and stored by the user. CaSTCo is developing guidance for the recording, formatting and sharing of data.
Cost: LOW. Around £85 including VAT for the instrument and then £17 for 25 tests (£0.68/test).
Ease of use: MEDIUM. The Hanna HI-713 requires users to handle reagents, dispense an accurate volume of sample and make sure vials are clean and condensation-free. Instructions are provided, and video guides are available.
Quality control: Local coordinators are responsible for quality control. Measurement is likely affected by extremes of temperature and turbidity, so a good idea to measure and record those alongside the phosphate measurement if possible. CaSTCo is developing guidance and templates to help with data QA/QC.
Coverage / scale: This can be used anywhere. It is currently used by many local/regional groups and as part of the Angling Trust Water Quality Monitoring Network nationally.
Health & safety: The reagent used is toxic if inhaled and can cause severe skin burns and eye damage, so care must be taken when handling. The Safety Data Sheet is available for download from https://sds.hannainst.com/. CaSTCo is developing appropriate health and safety guidance.
CaSTCo Investment: CaSTCo is reviewing and investing in this method to optimise data quality, ease of use, safety and cost, including rolling out training and investing in data systems.