One thing I forgot to ask is what light are you using? The amount of food your plants need will depend on the type/amount of light they are receiving. My early grows were with 500w of CFL light. Under CFL's I only used 3/4 strength food and never needed to add clamag in the 1st 2 weeks of flower. Under 250w of HPS I use full strength food and need to add calmag.