The minerals keep the gnats down. Topdress each plant 2 tbspn re-charge and water it in. It's no coincidence you have bug problems and plant problems....low minerals will mean low pH and low pH will lower brix and invite bugs.
It happens less and less as the soil gets tuned in....and then after 4 runs or so another type of problem happens. When the soil pH is too high from all the rock powders added and re-added, along with some salt buildup, the soil tends to invite mold, mildew and various other trouble with it.
The re-charge is designed to keep the mineral content up, hence the pH buffering it provides. It locks the soil in at 6.5.
Yep PM happened to me my last run but once they dug into the soil they got healthy. Not as healthy as I would have liked them to be but they made it. I think it was more me than the soil, I contributed to about 99% of it.
Add Pro-mix every 3 runs otherwise you'll have mud.