Hi Krissi-
Hey, if soil gnats are giving you problems, you should try some Mosquito Dunks
in the plant water- Dunks (or Bits) are made with a bacteria (BTI) that kills the gnat larvae in the soil.
Harmless to the plants, and just about everything except gnat and mosquito larvae...
Dunks are easy to use- just soak one in the water you're going to use on your plants (I use a 5 gallon bucket) It takes 24 hours for the BTI to populate the water.
Then, just water the plants normally with the BTI treated water, and within 2 or 3 waterings, the gnats will be a thing of the past in your grow room.
You will still have a few gnats until the adults die off, but once they're gone, they're gone!
The larva are what does the harm- they eat roots- but the gnats themselves are harmless to your plants-the adults don't eat, they only drink, so they're just an annoyance...but if you do the dunk thing, that annoyance will soon be gone for good...
And no more goo on the walls...