Description : Flourish Iron is a highly concentrated iron supplement. It should be when the iron requirements exceed what can be delivered by Flourish at the recommended dose or signs of iron deficiency appear (such as short and slender stems or yellowing between veins.) . This product should be in conjunction with Flourish and/or Flourish Tabs. Contains no phosphate or nitrate. 67.6 oz. treats up to 400 gallons for 4-6 months.