CalMag is a bit of a misnomer. It's a product containing both Ca and Mg. Typically deficiencies of these two elements will occur at the same time which is why 'CalMag' is offered as it is, ie. a solution containing both elements (Ca and Mg). With that being said, sometimes a plant is only deficient in one of the two elements and by adding both, a problem can be exasperated. There are amendments out there that allow one to tinker with either or while leaving the other alone. If you can rightly identify exactly what you have going on it will help you hit your bulls eye vs. the 6 or 7 ring. If you're having a specific issue, a picture would help, as would which specific Biobizz soil you're using. Just a little food for thought.