I’ve also used it outside (for plants in the ground) successfully. For plants in a container, unless you have moderately hard water (for calcium and magnesium), you’re probably going to have a hard time adding enough Cal/Mag because of the already high nitrogen (most cal/mag formulations use calcium nitrate, which will increase the nitrogen further).
Here’s the ingredients:
Ingredients: Total Nitrogen (N) (24%) (Ammoniacal Nitrogen (3.5%), Urea Nitrogen (20.5%), Available Phosphate (P?O5) (8%), Soluble Potash (K?O) (16%), Boron (B) (0.02%), Copper (Cu) (0.07%), Water Soluble Copper (Cu) (0.07%), Iron (Fe) (0.15%), Chelated Iron (Fe) (0.15%), Magnesium (Mn) (0.05%), Chelated Magnesium (Mn) (0.05%), Molybdenum (Mo) (0.0005%), Zinc (Zn) (0.06%), Water Soluble Zinc (Zn) (0.06%), Derived from Ammonium Sulfate, Potassium Phosphate, Potassium Chloride, Urea, Urea Phosphate, Boric Acid, Copper Sulfate, Iron EDTA, Manganese EDTA, Sodium Molybdate, and Zinc Sulfate.
They also use a lot of urea for nitrogen, which is less ideal than nitrate or ammonium for a plant with a relatively short period of vegetation like cannabis.
Still, if that’s all ya have...
Recommended dose is 1/2 teaspoon/gal