Hi Elsa,

Had the same problem myself in early summer in the first few weeks after filling the new pool. My chemistry was within all recommended ranges and I had the pump/filter on 12 hours a day.

A poster on this forum was writing about boatmen and backswimmers, so I asked him to describe the critters further, which he did; he was in OK and I'm in TX. Seems as if many areas of the country have these, as I believe another poster had them in IL.

Anyway, they're relatively harmless (a few do bite) and very resistant to chlorine (they laughed when I shocked the pool and invited more to the party). Best bet is to get a skimmer net and get a technique for flinging them up and out of the pool and then squashing them. Yup, if you don't, they'll crawl or fly back into the pool.

I had about 15-20 at one time. Managed to kill them all and have had only 1 or 2 since. Hopefully, it was just a seasonal thing.