Basically, they can live in the same water you can swim in. You can probably get rid of them with foamy algaecide, but that also messes up your water for YOU, to some degree.

You don't say if you have springtails, which are just there when they hatch, or water boatmen who can live there. But, if it's water boatmen, they can fly, and will mostly leave now that there's nothing for them to eat in your pool.