(My apologies if I'm in the wrong place.) You can knock them in the water and they stay on the surface and swim back to the side. I guess they're some kind of backswimmer? I'll post testing results later after I've tested today but have applied 2 shock treatments and chlorine and keep scrubbing, though this is three days into a fresh, new fill of water. The other bugs are dying, like june bugs, flies, ants, moths. I've always had issues with pH, TA and CH. Add calcium hardness powder as directed and it always tests way too high and we end up having to refill pool. Add muriatic acid accordingly and it still never gets it just right. :\ Water's clear and smells good, though. Thanks in advance!