CAL-MAGnon is a Calcium Magnesium additive used to increase CAL MAG levels and ward off common nutrient deficiencies.
This could be a much longer answer. If you are a coco coir grower you need it, in fact your plants will not thrive without it. If you are using RO water you need it, in fact your plants will not thrive without it. These are the common reasons any grower will need CAL MAG aside from them, nearly all professional cannabis gardeners have a CAL MAG supplement on hand. CAL MAG deficiency is the most common nutrient deficiency both indoors and out.
Yes, CAL MAG supplementation is common both indoors and out.
Yes, if you introduce too much CAL MAG at once or too often a build up can occur and this toxic build up (for the plant) can cause nutrient burn. Learning curves exist in all aspects of life, gardening , well let’s just say it has a few.