Fungus Gnats in numbers more than just a nuisance?

I have read that if you have a "phantom deficiency" meaning all your bases are covered when it comes to nutrients and pH and environment, you might have root issues, especially aphids.

I have also read over and over "fungus gnats are just a nuisance, not a damaging insect". I think this might be true for the few fliers some people have, but I think I have a problematic infestation. I put out the yellow sticky cards last week and caught about 1000 per card, times 12 cards (one card per plant) thats 12,000 gnats and each can lay up to 300 eggs!!! The larvae live in the medium and eat the roots and fungus.

I catch some runoff from my coco pots once every few days just to check it's EC and the other day I saw 14 larvae that came off in the 2oz of runoff I caught! I would say this is a huge problem, no matter how many people say they are "just a nuisance". I've reviewed all my sticky cards and have not found anything resembling a root aphid so I think this is all fungus gnats.

I've seemingly already diagnosed the issue but would like more opinions.

I have one plant yellowing pretty badly starting two weeks ago (week 3 flower). They are now starting week 6, day 35 and the fans are showing multiple deficiencies like P- and N-. pH going in varies from 5.7-6.2 and EC in is 1.6, out is 1.8, 100ppm higher which is fine. All 12 plants are now showing serious intervienal chlorosis and some are even light bleaching even though this strain has shown in the past to never bleach and the 1k lights are 24" above the canopy.

Does root stress/roots being eaten cause the plants to be more sensitive to high intensity light as well?

Can all this be just from the root stress from the gnats? I've already dealt with them using a combination of methods and they are dwindling in numbers but I think they damage has been done due to it already being week 6 flower. It's pretty apparent the buds are stunted this run compared to others so I'm in salvage mode now.

I think the gnat issue was caused by me using Great White and Root Excel which made tons of fungus for the gnats to eat, having 82F temps and having an auto watering system keeping the coco moist, perfect environment for the gnats to get out of control.

Let this be a warning for those with similar conditions to keep an eye out for the not so harmless gnats!

sorry about the gnates
you have a nice up there still good looking buds
i got gnats from discounted soil

Microbe Lift BMC (a type of BT)

Use this in your water tank/res. Add to feedings if doing by hand.

https://4hydroponics.com/microbe-lift-bmc-2-oz

Sounds like a secondary infection of Root Aphids is possible here.

Search for the answer to that problem on this site.
Look for a posting by me on a SPECIFIC pesticide FOR Root Aphids from Beyer Ag.
I don't have that info in front of me right now (Going to have to bookmark that).

Good luck

I use Gnatrol to provide microbes to the root system to kill the eggs, and yellow sticky's for the flyers. I push some stickies down to the surface of the medium, and that gets the crawlers. You have to use the Gnatrol early though, so they never get a chance to hatch. If they do hatch it will take 30 day's to interrupt the hatch. I've had them a few times, and I just try to control them with the stickies, and they really haven't done any damage that I could see.

I think another key in the future is to let the medium dry more before re feeding. I've used ground up mosquito dunks in my soil mix for a while now and it seems to help.