FloraFlex Cal+Mag+Iron is a Calcium, Magnesium, & Iron supplement designed to complement the FloraFlex 2-part base nutrient formulas. Some plants may require more of these elements under rapid growth and/or developmental phaes. The product corrects common deficiencies when using reverse osmosis water, as well as plants grown in coco coir, rockwool and/or any hydroponic growing media.