Would any of you be reluctant for any reason to switch to Jack’s in the middle of the grow? I’m about to flush salts out of FF HF during the 4th week of flowering and are considering switching mid-grow. I was using the FF Trio. @Myfriendis410
I’m following the 2.5g/3.5 gram Part A and part B plus 1.2g Epsom. Is there a need to add cal/mag with Jack’s + Epsom?
I switched mid grow on my last run from FF trio to jacks 321 and could tell a very noticeable difference in a week. I just switched from the 321 line to jacks for tap and the bloom and finish nutrients. If you’re using tap water I would look into the jacks for tap. Started this run on it and they are loving the base and bloom nutrients 
No need for the cal mag, it’s part B, cal nitrate.
And the Magnesium Sulfate (Epsom) gives you the Mg.
I would have no qualms about switching over. I’d likely make sure my runoff numbers were below 1,000 ppm though before going to Jack’s.
I would also recommend silica.
Switched to Jack’s on my third grow, FF Trio to Jack’s at start of flower.
No, it would not hurt or be an issue