.... Well, my first concern would be the pH of that HF soil, as Fuxfarms has been horrible these days about badly acidic, poorly cooked soil-- I'm talking in-bag pH's in the low 5's!

- I have tested several, even at the stores, to show the sales folks what's happening! ...instant problems, basically, but some folks seems to get the occasional bag that's still okay, and it sounds like you're one of them-? Otherwise HF is good, mild soil, less hot than Ocean Forest...Have you taken a pH reading of the soil? One thing I highly recommend is a soil pH probe (the Accurate 8 is a good meter for the money), for
direct measurement, vs. the dubious run-off method,... that one has several sources of potential measurement error inherent to it, but there is a "sticky" article here in the Infirmary, on the contents page near the top that helps limit them--
quickie reference for run-off testing,... Check it out, and you can even test the bag soil instead, since your plant/soil is still this young... soil pH is best around 6.5, to allow some wiggle room for natural drift,...as you've seen, feeds tend to be acidic, but well lime-amended soil can help buffer this beyond what you do after initial mixing and adjusting,... Point is, knowing what your soil pH is will dictate, in part, what you pH your feeds to, in order to help counteract or maintain what the soil pH is at the time...trust me, when it comes to pH, prevention is 10-fold easier than cure! Here's a great pH nutrient availability chart (from the defc. picture depot thread, here as well)-
.... EWC, earth worm castings, used to make a poop-tea! A great source of mild nutrients, and if the bag is in good shape and fresh, full of beneficial microbes,.... teas don't have to be complex, a simple one can just be about 1.5cups castings/gal dechlorinated water, with 1T/gal molasses to sugar-spike the 'crobes, or even add some inoculant to that as well to supercharge the 'crobe count.. bubble it for a day, then just pour it in, and top dress with the remaining muck!
... the Ca-Mg supp' early on can be 1-2 times a week (note if your soil is amended with lime--yours is), not every feed, or even to be necessarily included with the other feeds,.. sometimes I stagger things to keep the ppm count lower, rather than put everything in at once-- maybe water with just the Ca-Mg;,... however, note that the Ca-Mg can help buffer your feed solution, if that's needed; most are carbonate based, and it's the carbonates that do the buffering of acidic solutions,... Molasses can be a nice alternate supp', as it has some Ca, Mg, K and a little Fe in it, plus the sugars!

... later, near blooming and through to the end, use the Ca-Mg more regularly.... keep in mind, most base nute's have some Ca and Mg in it already, but some strains seem to be hogs; LED's seem to cause higher demand,...