I used garden safe pure neem extract. I'm in soil but it did not hurt plant at all. 20-25 ml per gallon to drench roots. It kills everything but the plant. And is uptaken in the plant and deters pests I'm not saying you have bug issue n I've only ever dealt with soil but if it's doing crazy things that you can't explain I would suspect something at the roots. People here blast me about my encounter with gnats and or alphids but once I put that neem on their ass the first time my plants did a complete 180. I had dead plants. Way past where yours are. And now they are almost flawless. 3 ft indoors about 2 weeks in 12/12 now. I got the neem right at a Walmart for like $5. It won't hurt plants. Stinks a bit. But all organic too.Sorry I forget you're soiless. Yah @xenon730 is right about that. Even if you aren't organic neem or karanja oil is the best IPM. Contains 200 different natural limoids that all just absolutely destroy mites. It prevents molting, reproduction and pretty much having any instincts to live at all. It also causes them to vomit profusely.
I use a tsp of neem oil, 1/4 tsp of aloe powder and protekt as an emulsifier. I put this in a quart of warm water. Shake the hell out of it and shake every once and a while during application to keep the oil suspended. Not to be used on flowers. The plant can absorb the oil systemically and it lasts about 2 weeks.
Don't go cheap. The nature's choice is garbage and even bonide. Get dynagro or neem resource.
The neem tree comes from india. People would wonder why all the crops would get eaten by locusts but they didn't touch the neem tree. It has been used for over a century.