Fungus gnats, means you are most likely over watering. Use these:

https://www.amazon.com/Summit-responsible-solutions-Mosquito-Ounce/dp/B01LN3TPXK/ref=mp_s_a_1_3?dchild=1&keywords=mosquito+bits&qid=1618429180&sprefix=mosquito&sr=8-3

Hi.

Regardless of what others may think,

One of the most frustrating pests in many indoor gardens is the dreaded fungus gnat and its young, the fungus gnat larvae. These little buggers can absolutely destroy your plants if you're not vigilant — and they can do it quickly. ... They also lay hundreds of eggs fast, which will devour plant roots!

I would either use mosquito dunk pellets sprinkled on the surface of your pots which they sell, or do an entire soil mix change over to a better porous one that does not encourage fungus gnat populations. Sticky traps work but not for the larvae.

Fungus gnats are a plague, depending on where you live. In some places they're just a symptom of your soil staying too wet, if you live by a marsh or wetland, or even just in an area with a lot of boggy areas nearby, they'll come in and nest on watering day no matter what you do. I happen to live by a marsh and they fly around in nasty little clouds during the summer and fall, and no matter what I do they come in the doors as soon as you open them. Best way I've found to eliminate them is to use mosqito bits in the soil on watering day, then a day or two later I cover the soil in a 1/4 inch layer of diatomaceous earth. The DE kills the adults, the bits kill the larvae. Usually takes care of them in about a week.

A layer of sand on top of the soil will prevent the adults from laying eggs too.