Three practical routes
| Route | Published detail | Checked price | Where it fits |
|---|---|---|---|
| Salifert nitrate + phosphate | Nitrate kit listed around 0.2–100 mg/L; phosphate kit covers low marine ranges with colour comparison | £9.59 + £9.49 | Low-cost, replaceable manual testing for routine trend tracking |
| Red Sea Algae Control | Combined nitrate/phosphate route with comparator-based testing | £66.99 | A bundled nutrient workflow when you prefer one ecosystem |
| Hanna HI-774 phosphate ULR | 0.00–0.90 ppm phosphate; 25 tests in the listed reagent pack | £13.40 ex VAT for 25 reagents | Useful when low phosphate decisions need a digital readout; does not test nitrate |
Do not confuse nitrate with nitrate-nitrogen
Check the unit and reporting basis in the instructions. “Nitrate” may be shown as NO3 or as nitrogen (NO3-N); the numbers are not interchangeable. Keep the same method when building a trend, or record the conversion clearly before comparing results.
Why low-range phosphate is fussy
At very low concentrations, a tiny residue in a vial, a dirty cuvette, a missed timer or an overfilled sample can move the result materially. Rinse with clean water, follow the reagent order and timing exactly, and repeat a result that would otherwise trigger a large change to feeding or phosphate media.
Use nutrients as a control loop
Record nitrate and phosphate beside feeding, water changes, skimmer operation and media changes. If phosphate falls while nitrate remains high, that is a system trend to investigate—not an instruction to dose blindly. Avoid treating “zero” as the universal destination; the useful range depends on the livestock, salt system and export approach.
Sources and limitations
Hanna’s UK listing gives the HI-774 range and reagent pack details at HI-REEFKIT. Current retailer examples include Salifert UK listings and Red Sea Algae Control. We have not independently checked colour interpretation or inter-kit agreement.