SeaChem Reef Iodide ™ is an iodide supplement for those with dense populations of invertebrates or soft corals. It is also useful in tanks with aggressive skimmers. Reef Iodide™ is concentrated at 8,000 mg/L. As little as 1 mL in 160 Liters (40 gallons) will raise iodide to natural seawater concentration. It is formulated to provide a safe source of iodide that will not convert to toxic free iodine under storage or reef conditions. It is recommended that this product be used with the MultiTest: Iodide™ test kit to ensure proper maintenance of iodide levels. 250 mL treats 20,000 litres.