Hi all, any ideas what these are. They are all over my top soil and crawling round the top of the pots

Diatomaceous earth helps and wont hurt your soil or plant.

Ah pests! Here's more info on aphids: https://www.growweedeasy.com/cannabis-plant-problems/aphids

Looks like the root aphids. Sadly they're really hard to get rid of. Best bet is drenching your plants in something that will kill them. Ive always just tossed the whole grow and sanitized everything and started over. They multiply extremely fast and are a PIA.