are you useing a soil based medium or soil-less medium reason i ask i found out recently that a mix of peat moss, perlite,vermiculite is considered soil-less which made no since to me but followed there advice and switched to a lower Ph of 6.5 as i was watering with water Ph to 7.0 and since switching a few weeks ago my girls are now growing quicker and bigger faster as it could be the start of a magnesium defiance or iron defiance just depends on the type of medium you are useing