zinc and magnezium tablets

hi my plants seem to have zinc and magnezium defficiencies, ive lowere the ph as it was a little high, i have some ZMA supplements i take myself made of zinc of magnesium, if i open the capsule its quite a fine powder, i was wondering if adding a little of this powder to the water would help? im using bubbleponics btw vedging them
also if this is a good idea roughly howmuch do u recon i should add per liter?
thanks

Hi : ) I'm using soil and was wondering if this method would work as well.