mass exodus of mites from my soil after a flush...

i may be just a beginner but I dont thinks your dealing with spidermites. Maybe you could post a pic? Could it be fungus gnats? The matured adults could have been hanging out in the soil and got rushed out when he flushed.

I agree the flush brought the gnats out, I like sm90, and neem oil or azatrol, if preventative spraying is done usually nothing is needed for flowering, sm-90 is only used to kill em though no need to through it in your soil all the time. for preventative matinace on roots cannazym is good or any multi, zym, personally I think canna makes the best one, and hygrozym being the second best, with AN's Sensyzym coming in third, but their all good.

if this happens all the time I sugest looking into vermi-T, but it is not available everywhere so cannazym and neem for preventative.

Weeeellllll, There could be both, mites and gnats. The yellowing sounds premature, so it could be mites causing that. Look on the bottom of the leaves.

How to prevent? You have to use a powerful insecticide at any opening to the grow area. Air intakes need to have a good dose sprayed in when the fans are off. All corners of the room after washing the entire room with a chlorine/water mix.

Then, during Veg, at a minimum of once a week spray with Neem oil, about an ounce per quart, shaken, water should have set and not have chlorine. Spray the leaves. Once you go into flower, you want to not give too much after the first 3 weeks. You can also put about a teaspoon to tablespoon in a watering and give one dose in late vegetation directly into the soil, the plant will uptake enough to keep the mites away. You may also read the link I have on mites.

Gnats, are a real PIA but not something that will damage the plant. I found outdoor soil brings them in. Regardless, I keep a sticky fly tape in the rooms to get the stuff that flys.

Right! sm90 also works for me. fungus gnats sucks! if low on cash try mosquito dunks in a bowl of water