Do powerfull LEDs cause plants to use more calcium and magnesium ect ect ect ?

The light intake will help the plant to create more chlorophyl. This will help increase the size of the plant in general, bigger buds. So you can increase nutrients Intake slowly to avoid nutrient burn. Calmag is nice to add but mostly if your plants are experiencing such deficiencies. Happy harvest. Btw, read this article regarding calmag it might help https://www.thcfarmer.com/threads/there-is-no-such-thing-as-a-cal-mag-deficiency.62747/

Generally the stronger the light the more food they can use, but it's best to start flower nutes low and work your way up. Better bigger buds when a little underfed, tiny little nuggies when overfed. Cheers friend