I'd wager some pale leaves/less vigorous vege growth - OR - P/K toxicity at some point (i'd guess P before K), which p or k tox can lock out numerous other molecules. Depends on how it is instructed on label... but 5-4-9 on its own will fall in this spectrum and very likely have issues.
it's not a good ratio for a seed-to-harvest formula. It's missing more than 1 trace element. it is ass-backward to pH-adjust water before you add something. If it is buffered, it is buffered "to" a pH value. 'buffered' means it has elements dissolved that make the ratio so large that when you add other things to it, it cannot change the pH much due to proportions involved. thus, pH-adjusting water before hand would be a total waste of time and uneccessary if actually buffered... ffs, that's what buffering means.
lets say you got 1000 h3o+ : 1 oh- ... you add just a little bit and this ratio, or pH of 5, can quickly change.
now, you have 100000000 : 100000 is still 1000:1 but if oyu add someting donating X protons (an acid) it would take a whole bunch to change the pH of 5.
hydronium to hydroxide ratio is an easier way to describe pH. the ratio stays same, but numbers are very large relative to what acids or bases you might add to the solution. it is the natural/predictable outcome of H+ activity in a solution.
solutes are in a solution.. not salts. this isn't 1950.
None of this is directed at
@ezzjaybruh . It just needs to be said in regard to this product. The item description on amazon is batshit crazy.