I believe the fungus gnats in commercial soil has to do with where the bags were stored before shipment. The wholesaler we get our soil from stores their bags on wooden pallets inside a temp controlled warehouse(I know because I've gone down there). I believe some wholesalers cut corners "so to speak" by storing their soils outdoors where pests can get at them.

The commercial soil I've been getting at our shop does not come with even a single fungus gnat! Not yet anyway...
Even the ROOTS organics which was known a few batches ago in the mid west and east coast to have fungus gnats is completely clean. Again, I believe it has to do with where they store their mixes.

Peace,E1

Good point re: gnats in commercial soil. Yet another reason why I stick with the prepared stuff e.g. ProMix. Never seen a single bug in this stuff, and you can believe me when I say I've opened a LOT of bales over the years.

hey guys i am useing a aero 60 and just found these little buggers 2 days ago so i pumped out my res and tubes pulled out all the plants which by now had root rot so i cut off all the badd roots and set them in a tray wile i clean room and system with bleach mixed with water. then i put the system back together. then sprayed the under side of the leaves with a strong mix of water and scotts bug-b-gone (Pyrethrins). after doing this i filled my res back up with 45gal of water and my nutes as well as 6.5L of h2o2 and turned the system on and shut the room up. now the next day i looed in my res and did not see and on the top of my water like the day before. but i did spray alittle bug b gone on top of the water so that nothing could live there least for a day or 2. does anyone have any other ideas as i think i got the adults as i am not seing any of them but its larva that i care about. is there anything else u guys think i should do as i am 3 weeks and 2 days into bloom and it would suck to just have to cut them down as the toronto treat yourself fest is the end of may and i would like to have some good stuff to go with

Hello guys, I'm a new member and fairly new to growing. I am currently in week 13-15 of this grow,don't know precisely with out my calender, I'm using foxfarm ocean forest soil and nutes. Running and 18/6 hr light cycle on 4 ladies under a 400 MH. I have been having several issues with fungus gnats as well. I have been trying everything from diatomaceous earth to, as of most recently, a product called Sierra Natural Science. The diatomaceous earth seemed to work to kill adults and larva at first. After about a week I seemed to have an explosion of these guy's. I have applied the natural science twice now and I am still seeing them... I am clueless as to what else I can do if anything. Other than these guys my ladies seem to be doing just fine. Ph is ideal and plant growth is steady considering 2 are coming back nicely after a slight burn from a Neam treatment.

Sticky Fly strips or cards work. As well as putting potato quarters on the soil daily. The flies lay eggs in the potato and not the soil. People have good results putting a layer of SAND or pearlite over the soil.

well i did go get some fly tap and some more h2o2 for when i need it as well not seeing any adults and its has only been 3 days since i found them. so any other ideas. as well when i go to hand water them with the system off how much bug b gone should i mix with water so that i can hand water them to help kill off the larva help please

Since, applying the Siera Natural Science insecticide, thus far I have started using yellow sticky fly traps and those are definitely helping. I also took out as much top soil as I could without disturbing the root mass. And replaced it with new, fresh soil that I just bought. Also I placed some several small cups of sugar sweetened coffee in each pot and that has definitely helped to draw out the adults. Is there any type of particular sand I should use for to cover the soil with ? And would the pearlite alter my Ph ?

well any sand should work and as for the perlite i don't really see it changing the ph as all good soil and soilless mixs all have perlite in them

can any one tell me how long of time as in days or months should i let go by with out seeing any adults ontop of my water before i can start thinking they are gone. remember i am in my 4th week of bloom. and how can i tell if they got into my veg room or not
wish i new what the lara looked like under a microscope as i have one just don't know what i would be looking for as when i found them in my budding room and looked at some water under the microsope i found what looked like maybe 3 different things and one was eating another. so i guess i could do this 4 my veg water but again not really sure what these larva look like

Alright my fungus knats are back, just got my shipment of beneficial nematodes, lets see how they work. If anyone else has used them, tell me what you thought.