Fight fire with fire! Use a preditor mite (nematodes)that feeds on the eggs of other mites. Ask your local hydro store guy for available products. Pesticides may hve better results but use only durring veg and only whts needed.
Using natural pest control methods such as watering with a diluted nematode solution and being careful not to introduced any foriegn soils into your room will help keep the mite & gnat population under control.
The plant looks healthy and leaves have a good even coloring. But instead of blades broadening and stretching outwards like this: _._ ,they seem to angle at about a 45° angle like this: ./
