Garden of Green - Kosher Kush

I have a grow with two earthbox jr. in a 3x3 using BAS 3.0 soil, gnarly barley, craft blend and build a flower prior to placing into flower two weeks ago. I do not use a plastic cover for the earthboxes and noted that my humidity remains around 50-70% RH throughout the day with an AC Infinity 6" exhaust fan on continuously. The media is wicking the moisture and may require me to add a dehumidifier to keep RH lower in flower. The reservoirs are emptied daily (1/2 gallon reservoir for jr.) The plant growth is extremely vigorous. I check the plants closely, and last night when the lights came on, the floor was alive with black fungus gnats. I could see them emerging from an area by the fill tube where they were just pouring out. They lined the tent floor and around the sides of the tent sitting on the edge of the floor tray. I inspect my plants closely performing maintenance twice every day and perform duties such as defoliation of leaves to prevent occluding bud sites and scrog net adjustments. I would have seen this condition and noted nothing out of the eight hours prior. I had the sticky cards and placed several in the tent. I also had mosquito bits having seen a video months ago and had purchased some in case. I dropped some in the reservoir of both earthboxes and on top of the media of my grow. I keep negative pressures in the tents to prevent a problem like this from spreading but also treated all my plants with the mosquito bits and cards. If the bits and cards are not enough, I will also include beneficial insects and nematodes to control if necessary. Any other suggestions? The cards were covered by morning, and I will replace them to continue monitoring the condition. I was incredibly surprised how quickly this issue occurred. My thought includes the amount of wicking occurring into the environment which may have led to this condition along with the subsequent replenishing of the reservoir. Thanks again for all you do. I have growing for 2 years but this is a first grow with earth boxes. UPDATE I have been allowing the reservoirs of the earthboxes to go dry as the soil is extremely wet measured with a moisture meter. I had placed mosquito bits to the topsoil and the reservoirs to allow the bacillus inoculation to take hold in the media. I have been cleaning the tent daily as well to discourage hatched gnats from roosting on the sides of the tent floor tray. I change sticky cards daily as well and created a IPM with the mosquito bits by adding some to water and then filtering out the solids leaving some of the bacillus behind. I then applied via sprayer to topsoil and tent floor tray lightly. Noted that this killed the gnats immediately on contact. Will repeat tonight if necessary, otherwise I will wait for next hatch cycle to eradicate them as quickly as possible.