Calmag

ATA CalMag is a supplement designed to provide the plant with calcium and magnesium when the nutrient water is deficient. Although hard tap water is rich in calcium and magnesium in most countries, in some cases a CalMag supplement may be advisable. Especially if the grower is using soft tap water, as in much of the UK, or reverse osmosis (demineralized) water, the use of CalMag is even a must for the plant.

The use of ATA CalMag is also recommended on coir substrates. Growing on coco carries a higher risk of calcium and magnesium deficiencies than growing in soil or hydroponics.
Both calcium and magnesium are secondary elements, meaning they are essential for healthy plant development. The only difference from the primary elements (NPK) is that they are required in smaller amounts.

increasing nutrient absorption
stronger plants
Stimulates better quality flowers

Use:

Add 0.1-1 ml Calmag per liter of nutrient solution.

Use Calmag to fortify low-calcium and low-magnesium water or add it to your regular fertilizer solution. Use water at room temperature (21°C) for best results.