how to be certain fungal gnats are not in new soil

[Rich800]

Getting ready to start a new grow. My last one was plauged with the dreaded fungal gnats. Anyone have any trick or suggestions to be sure they are not in the soil I purchase? And the best ways to avoid getting them.

[showstopper]

never tried it but ive heard that you can low heat bake you soil to kill shit, or maby freeze it?

[Skihigh]

Do some research on diotomaceous earth.
It'll work for you.

[devilvenom]

Do some research on diotomaceous earth.
It'll work for you.

if you dealing with just a few plants, this will work good, just did it to my bonsia moms, if you got a shit load of plants.... well.... i just started using mosquito dunks so i can't give conclusive evidence, but i've read a lot of recommendations, kills the larva not the flies.