I have started to add approx 1 tsp of Epsom salts to every gallon of feed along with 1 tsp dissolved blackstrap molasses .
I thought i should point out that these odd combinations of beneficial's have been tried and tested and provided you don't over do the molasses you won't get any funky smells or root problems. and please, before i get a flurry of "don't mix organic with chemical" this is Just an observation, but interesting nonetheless.