Bud factor x. Is it worth it. ?

Hi guys. I'm at week 7 of my flowering a lot of my leaves are curling up turning yellow at the edges. From my understanding it's lacking magnesium. I was told by my hydro guy to buy bud factor x ? Damn thing is a 100$ is it worth it

My dude at the hydro store said he ran it ..it was lookin all good all crystally then it hermed on him ;( I wud say no go with cal mag if u have a mag def.