Rootrot , Fungus gnats,growing in soil, HELP

i just noticed i have a fungus gnat infestation and mild rootrot, growing in promix and compost mixed 75% promix and 25% soil(compost)

You may be overwatering. Wait until the soil dries out, about an inch deep. Then it should be ok to water again, but keep it minimal. Also, put an inch thick layer of sand on top of your soil. It will kill existing gnats and eggs, plus keep them from reappearing. I had this same problem, and it fixed me right up. You can also try some sticky traps in your box/room to catch/kill the ones flying around.

I've got a fungus gnat problem at the moment myself. I grabbed some random granule thing from the hardware store that is suppose to kill them, and prevent them from feeding on the roots and stuck up fly paper strips...seems to be keeping things contained...won't know for another couple weeks if it works to break the life cycle or not, we shall see

go to the hardware store and buy mosquito dunks. soak them in the water ur going to use for a while then water like normal. and i use diatomaceous earth instead of sand (havent heard of that) to put on top of my soil. the difference being the d. earth is food grade so its really safe for your plants. dont go outside and pick sand up and use that. havent had any gnats in a year and they were BAD when i first started. hope this help.

Thanks for advice.

i think turning up the fans helps......if nothing else it pushes them into the fly strips........

Honestly, all you need is sand. you don't have to buy any special products. Don't over water and you'll be good.