When I did my routine inspection of my house plants I noticed small grey bugs bustling around in the root and lower stem zone.
This seems to affect a big portion of my ~50 plants. I didn't inspect every pot yet, but they are hard to notice, because they only swarm out when I shake the container or flood it.
I believe those are thrips or springtails, but I also believe it doesn't matter much anyway, because I want to get rid of them ASAP. But I can attach some microscope pictures if somebody is interested :)
I already treated a few plants over the last few days by filling up the pots with lukewarm water, a drop of very mild surfactant (Coco glucoside) and a splash of hydrogen peroxide. I let it soak for half an hour or so and then flushed it out in the shower.
This seemed to help, but would be a huge pain to do for every plant I own, and if there's one bug or egg left, I can do it again in a few weeks.
Therefore, I need some kind of insecticide. Neem oil is the old classic, but I don't want it to be in the substrate itself, because if it decomposes, it might leave a big mess.
Are there any more potent or common alternatives out there? Can you recommend something?
Any ideas what I should do next?
Edit: These seem to be springtails. Here are a few pictures under the microscope:
