Does anyone have any effective remedies for getting rid of fruit flies and knats that come into the house through plant soil? No matter what soil I buy I always get them but I can never get rid of them. I've tried buying fly traps (sticky and liquid), I've used bowls of soap water, bug spray, apple vinegar water, cinnamon, etc. Nothing works!!! I would really like to get rid of these little pests so any suggestions are appreciated. None of the normal remedies seem to work.

How are your plant hygene practices? Are you using quality potting soil or outside yard soil? Is it free from debris?
Fruit flies do not live in the soil but may spend a lot of time seeking shelter there. Fungus gnats thrive in poor, debris riddled soil. I have always used a high quality potting soil, kept the soil free of dead leaves, shoots and twigs and have never been bothered by these pests.
Also how is your watering schedule? Watering too often can promote fungus gnat development.
Also over ripe fruit in the home such as apples and bananas can draw fruit flies.

Have you considered an insect eating plant like a pinguicula or pitcher plant? You could put one next to your other plant and nature would take its course

I have used Pinguiculas too, and gnats love them, however, Pinguiculas undergo a cycle when the leaves are not in sticky mode, so it will not help at that point. But when they are sticky, goodbye gnats, attracted to those carnivore leaves like a magnet

Planturion, you can also add some more pumice or perlite to your soil surface, to hasten dry out time. Gnats thrive in wet media. You also have to change your watering regimen, especially during the cold season, a bit less watering to help the soil drain and add good airflow at root zone. Then you can further augment your efforts with those yellow sticky traps to help further catch those flying bugs.

The sticky traps alone will not work, unless the watering aspect of the media is not improved.

I water my plants roughly every two weeks, and they do tend to dry out fast because the heat gets pretty warm in my apartment. I do not use outdoor soil but I do use organic. I keep my plants very pruned and clean. I have a venus flytrap, but as the bugs are so small it's kind of useless for this situation. I was thinking more of things to add to the soil like a solution or powder that isn't chemical or harmful.

Fungus gnats are very frustrating because they are so noticeable and annoying. To be successful in eradicating them, you have to understand how they live and reproduce.

The larvae live in the soil and are usually introduced when plants are repotted using a contaminated potting mix. Unfortunately, most of the brand-name potting mixes contain ingredients such as compost, soil, and bark chips all of which harbor gnat larvae. The fact that all of those ingredients are "organic" is meaningless and is just marketing.

A pest-free potting mix will contain only peat moss or coir and perlite and some lime. You have to read the fine print ingredients list on each bag to learn what's in it. Pro-Mix is a good mix if you a find it. Otherwise, make your own potting mix by mixing 4 parts of peat moss with 1 part perlite.

In my experience, people tend to repot unnecessarily and that can cause other problems. Best to repot only when absolutely necessary.

For existing plants that are infested, you have to deprive the larvae of moisture they need to survive. They live mostly in the upper layer of the soil. Start by removing all loose soil from the surface that is not in immediate contact with the roots. That will remove many of the larvae. Then, allow the soil to dry as deep into the pots as possible before adding a small quantity of water. Most plants can withstand drought more then you may realize. Try to keep the plant hydrated just above the wilting point.

Keeping the soil dry will gradually eradicate the larvae and you should see a reduction in the number of adult flying gnats. The adults die of old age in about a week. Avoid any treatments that involve adding liquid to the soil.