I'll look that up, thanks. Hydroponics Cal Mag solution does have Iron in it, I just don't use it as often as I should maybe, Once a week might not be enough, these ladies might be growing faster than I think they are. Have no idea, first grow. I topped it this morning with 6 cups of the solution just in case. the soil is still wet from Sundays watering. Not supposed to water them till Thursday, let the water evaporate some so not to drown the roots.