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Seachem MultiTest Phosphate

Seachem MultiTest Phosphate - Main image
$9.31 $13.49 In stock

Category: Aquarium Water Test

Seachem MultiTest Phosphate Test Kit

Phosphate in natural sea water ranges from less than 0.01 mg/L to 0.3 mg/L. For corals in reef aquaria, such phosphates should be 0.2 mg/L or less. Phosphates are non-toxic to fish and most invertebrates, but are ideally kept below 1 mg/L to minimize algae growth. In freshwater, phosphates are not critical and the allowable concentration is dependent on variables such as nitrate, manganese, iron, and vitamin concentrations, as well as the extent of use of live plants.

MultiTest Phosphate measures inorganic phosphate to less than 0.05 mg/L, producing a unique easy to read yellow-green-blue color range in marine and freshwater; however, usually, freshwater phosphate concentrations will be beyond the range of this kit, and dilutions of the sample with distilled water will be required. It performs over 75 tests and contains a reference sample for validation.


  • Measures inorganic phosphate to less than 0.05 mg/L
  • Multi-cavity plate for simultaneous testing of up to 6 tests at the same time
  • Includes reference for test validation
  • Marine or freshwater
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Customer Reviews (4.8 / 5 · 4 reviews)

Jacob I. ★★★★★

The kit measures down to that super low range for reef tanks, so I can finally keep phosphates below 0.2 mg/L for my corals. It took a few tries to get the titration right, but the instructions are clear enough.

Eva ★★★★★

Finally, a phosphate test that doesn't leave me guessing—the color chart is dead simple to read, and it clearly shows the 0.2 mg/L cutoff I need to keep my corals happy. Compared to my old kit, the results are way more consistent, too.

Elizabeth Y. ★★★★★

I've been using this kit for a few months now and love how the reagent vial lets me measure exactly 5 mL for consistent results. The color chart is clear enough that I can spot even slight changes in phosphate levels, which helps keep my corals healthy.