Just got a new bale, eh?
There are a dozen different S#4 formulations.

I liked my first bale of Sunshine mix so much That I grabbed another bale as soon as my hydro shop got new stock.
Seems their "Aggregate" mix is pre-nuted differently and I burned some fans off by feeding too early.
(Gave 'em 1/4 strength when the cotyledons shriveled, 'cause this strain is not a heavy feeder)
Now, they get plain water until the new terminal growth starts to pale.
I'll read the bag carefully, in the store, next time.

We might have found the root of the problem here, by blind luck.
("Even a blind pig, finds an occasional acorn")

Aloha,
Weezard