Umm...the way your plants are grown doesn't determine their gender..thats like saying "I watered my plants with my left hand and now they are all male..next time I'll use my right hand!"
Hydroponics gives you a higher yield..it's cleaner..and you eliminate any chances of soil-bourne disease or pests..
Epsom salts and Cal-mag are sources of magnesium (I am not sure..but cal-mag might also contain calcium??)
Epsom salts are available at any drug store..give 1 tablespoon to 25 liters of water...