Awesome!! This is most helpful for sure!! That’s not something I even knew existed. I will have to go through and check all of my ph levels again thoroughly as well as my roots. Any idea how to identify them? I’ll also have to do some research regarding these little bastards if it is them and have a new plan of attack. I also attached the section I’ve been reading regarding the gnats.
Keep in mind, the picture associated with the fungal gnat infection you posted is a severe case. When fungus gnats are killing your established plants, like in that pic, you would have gnats everyyyywheree. As far as identifying root aphids, I suggest the website I posted earlier:
https://waytogrow.net/blogs/articles/root-aphids-no-they-re-not-just-fungus-gnats.
This is what I would do, in order.
Determine if they are root aphids or not.
Check your pH
Try a hydrogen peroxide treatment for the gnat larvae if they are indeed fungus gnats.
Improve watering frequency...they thrive when you water too often.
Put out sticky cards to catch the adults.
Increase air circulation.
Check pH again.
The tricky part is figuring out if the physical symptoms of your plant is caused by a nutrient deficiency (or excess), pH imbalance, pest infestation, or a combination of them all. So in this case, I might treat for fungus gnats first, then do a pH check, if that checks out OK, then either it's a different pest causing problems, or too little or too much fertilizer.
Another thing to keep in mind is how the plants leaves are yellowing. If they yellow from the bottom up, more than likely a deficiency. If it's top down, you can pretty much rule out a nitrogen deficiency. Look into mobile and immobile nutrients. I think mobile nutrients will start from the bottom up and immobile show up anywhere. I'm not an expert though, far from it, just trying to help.