Provides a Source of Calcium and Magnesium ATA Calmag delivers a source of two important secondary macronutrients: calcium and magnesium. These two nutrients can usually be found in sufficient quantities in hard water areas, but need to be supplemented in areas with soft water, where the dissolved mineral concentration is lower. As plants progress through the bloom phase, the demand for calcium and magnesium goes up, so most growers can benefit from using Calmag at this time, especially if they're adding big doses of PK boosters (phosphorus and potassium). Calmag is also beneficial for growers in coco. As coco coir breaks down, it can release extra potassium which raises plants' requirements for calcium. Atami ATA Calmag works a treat with an array of plantlife, including vegetables, fruits and herbs. The dose can be tailored to meet your plants' exact requirements.