I think they are "springtail" and should be harmless, although gross if you know they're in there. We had a lot of rain this past week and the pool filled up and the drain was clogged. I had thousands of these things again. I don't know of any way to get rid of them. If they're congregating by the sides of the pool and jumping back and forth, then a mixture of 1tblspoon dawn soap with 1cup water in a sprayer will cause them to sink and drown. But from what I've read, they can come back almost as quickly as you kill them...

Robert