Springtail or Water Boatman bugs?????

[AnnaK]

Wikipedia is your friend

http://en.wikipedia.org/wiki/Backswimmer
http://en.wikipedia.org/wiki/Corixidae (Water Boatman)
http://en.wikipedia.org/wiki/Springtail

Backswimmers swim upside down near the surface of the water. They are predatory and bite.
Water Boatmen swim near the bottom and don't bite.
Springtails are very much smaller than either of the other two and are probably not what you're seeing.

I seem to remember a discussion by Waterbear elsewhere that adding borates to pool water helps keep these insects under control.

[Watermom]

Boy --- that springtail is ugly!