If you have tiny white splotches in your leaves or if it's bad your bottom leaves will start dying it could be thrips. Thrips are very tiny white flies and if you can physically see them then you may have got em pretty bad. Thrips could explain the issues you have been having recently that everyone thinks is ph/absorption related.
Luckily it's super easy to kill them if you do have thrips...just get some Monterey garden spray and spritz the plant. Spinosad is the active ingredient. It's even ok to lightly spray the buds as long as you've got 10 days or more before harvest. Just a couple applications should do it but do it again a few weeks later just to be sure they are gone. Neem oil will also work but it takes a bit longer to work on them. If you add neem seed meal as an amendment to your mix & recycle the soil it will act as a natural defense against them. Only trouble with thrips is that once they damage the leaves they won't recover they will just wither & die. So if you catch them early it's not a big deal but once your plant is defoliated by then you will have to give them more veg time to recover.
