I have a 5 Gallon(3.5 Gallon Fill Level) DWC bucket in a sealed grow cabinet. About a month ago I noticed these small white bugs crawling around on the inside of my level meter. I immediately took the lid off of the reservoir and found no evidence of them inside. I checked today and found quite a few of them. After doing some research online, I've determined that they're Fungus Gnats in very early growth stage. Now, on to the strange part. The plant looks perfectly normal for it's growth stage(late flowering), the root structure looks normal, and nothing seems to be adversely affected. The cabinet is extremely well ventilated and exchanges anywhere between 100CFM to 450CFM depending on temperature. I top off my reservoir and balance PH daily and replace my nutrient solution every 3 to 4 days(it drinks a lot!). I've read many posts about these being a problem in soil based grows but never in hydro. What I'm having a difficult time figuring out is the following.... 1) How did they get there in the first place? 2) How do they continue to survive inside the reservoir when they don't have any light or means of escape from the bucket? 3) Why do they continue to reproduce even though I cannot find a single adult(dead or alive) anywhere in, on, or around the plant or cabinet? 4) What can I do to get rid of them without hurting the plant? Thanks for your help fellas.
Spray neem oil on leaves just in case. Use a water/hydrogen peroxide mix in your res to kill eggs. Check medium for larvae and eggs. Leave a chunk of peeled potato out to attract them and then throw potato away.