FloraFlex Cal + Mag + Iron Nutrients - 5 GallonDescription FloraFlex Cal + Mag + Iron: FloraFlex Cal + Mag + Iron is a calcium, magnesium and iron supplement designed to complement the FloraFlex 2 part base nutrient formulas. Some plants may require more of these elements under rapid growth or developmental phases. The product corrects common deficiencies when using reverse osmosis water, as well as plants grown in coco coir, rockwool and any hydroponic growing media. How to Use: Reservoir