This kit combines the Silicate, Phosphate, and Iodine/Iodide kits into one kit. MultiTest™ Reef Special performs over 75 tests and contains reference samples for validation. Silicate The silicate test measures silicates to less than 0.5 mg/L in marine or freshwater. This test measures soluble silicate and reports it as silicate concentration. To convert to silicon, multiply by 0.3. Phosphate The phosphate test 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. Iodine/Iodide The iodine/iodide test offers a quantitative test for this important element of soft and hard coral growth. It measures iodine or iodide to less than 0.005 mg/L. The color scale peaks at 0.10 mg/L.