sugar or molasses (mls works best) are good to help them metabolize nutes. i reccomend you get greenlight super bloom to use in flower; that stuff is ABSOLUTELY AMAZING!! its basically a super phosphate with a nice balance of n and k. i stopped using mg in flower and found it affects taste, but not potency (mg makes it taste floral and perfumy, even when stopped two weeks b4 harvest and flushed four times....)