Cripes, I knew all along I was wasting my time posting that sage advice. swoosh right over the ol noggin.
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Hey guys I have a root aphid and fungus gnats infestation!!! Need help wanna kill these fuckers ASAP !
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Whatās bt?
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BT = Bacillus thuringiensis
For fungus gnats: BTI = bacillus thuringiensis israelensis
There some examples above such as microbe-lift or those mosquito control pucks at HD. Your local greenhouse supply may have it as well in different forms.
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Donāt forget to check out the steel wool option 
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Items you need
Bamboo skewers. $1
Yellow party plates. $1 ]
Petroleum jelly. $1
Multi purpose sand 60lb bag. $4-7
Small coat of jelly of yellow(blue is good for other pests) sides of plates for cheap sticky traps for adults.
Use sand to make a 2 inch layer on the topsoil.
Done.
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This works. Iāve been fighting gnats because I use blumats and my soil is never dry. I put BTi in the rez and they were gone in weeks. Now im not using blumats but I water from the rez with BTi in it. I think I will be able to keep them at bay with BTi as a preventative for now on.
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Chop all the plants down and Nuke the room.
I always put soil in black plastic bags in the full sun for a few days or bake it in the oven the bugs will all die in there. I act like itās a hospital type clean room.
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What are the skewers for?
Hang the party plates off them, spear the other end into the soil. Some insects are attracted to the color yellow (e.g. yellow party plates). Similar to those horticultural sticky strips. Itās usually meant more as a diagnostic than a remedy.
The sand ( diatomaceous earth, gnat knix, etc ) is the remedy for his technique.
Iāve done something similar but in conjunction with BTi or other techniques.
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Stratiolaelaps Scimitus mites, Steinernema Feltiae nematodes, and Dalotia Coriaria (rove beetle) are all options for controlling fungus gnats in soil beds that need to be kept moist. I occasionally see a gnat, but also see the rove beetles hunting them down. 
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Sorry, for sticking into the plates. but you can honestly lay them, hang them anything really theyāll find them haha. Iāve even had a friend that used to used rolls of yellow tape but I could not find any at the time. Contact adhesive or double sided tape and yellow/blue laminated construction paper work as well.
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I have them pretty bad right now in flood/drain hydro. Iāve tried everything under the sun, with low success. Next run, Iām going to be covering all of my pots with mesh netting.
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I had them really bad once and I have a very easy fix to never get them again. I mix about 1/4 cup of mosquito bits into 5 gal of soil. Hever had them again after that. Also I never open a bag of soil and use it right away. I dump it into large totes and let it dry out for about a week before use.
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Did you try the Excel yet?
@advancedbuffalo told me he found success with it in hydro. Iām still gnat-free over hereā¦not a single flyer in over a year.
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Tried em. I also use Microbelift BMC BTi. It might help my numbers a little bit, but doesnāt eliminate. Iāve used BTi in the reservoir and pouring over for an entire grow, and had yellow cards 100% covered on both sides.
I tried it on some young plants in hydro. It didnāt seem to work, but I canāt tell if thatās because they were coming in from elsewhere. My wife has veggies in the basement and I didnāt use it on my flowering tent either. So Iām not 100% sure. It didnāt kill the algae on my RW, which I had thought it was going to do. Thatās their food.
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Need higher doses to kill algae it only slightly discourages algae growth in normal doses, but the doses required to kill algae seem to have a negative effect on the plant growth. Doesnāt kill the plants, they just donāt grow as fast. You could ramp it up to 2mL/gallon for faster results.
Takes a couple weeks or so to eradicate, Iād try it on all plants and see if it knocks out the problem. I now think it doesnāt do much to the adults but kills the larvae/eggs or prevents the adults from breeding.
Good luck, theyāre annoying as hell.
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Iāll try a bit directly on some larvae and report back. I can usually find some in the bottoms of my pots.
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Using concentrated BTi requires a specific use pattern to eradicate - gotta break the lifecycle. I use Gnatrol, but itās essentially the same thing, if not maybe in the same concentrations, and it works every time as long as you follow the directions. Hereās the lifecycle:
The pattern suggested by Gnatrol is a heavy dose every 5 - 7 days, repeated 3 times at least. So youāre looking at 2-3 weeks to break the lifecycle. Of course, combined with yellow sticky traps. And then, because you may have a few fliers left over, youāll want to do maintenance doses on the same schedule to keep them from reproducing for the next couple weeks after the heavy dose cycles.
I do that in soil if I get an outbreak and it always helps. Sometimes I get caught off guard by an infected bag of compost, and if you follow that protocol, theyāre gone in a month.
If for some reason that doesnāt conquer your gnat problem, they might not be gnats. Several other small flying pests look very similar and can be hard to diagnose.
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This Product works very well
https://doctorzymes.com/mo/index.html
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