Parasites in Tank

I noticed recently very small critter crawling on the glass above the water
line in my tank, as well as sort of hopping on the surface of the water. I
can't seem to see any below the water line. They are very small, so small I
can barely tell they are critters until they move. They are plain white is
about all I can see.

No new fish have been added to the tank, and no new plants.

Any thoughts?

--
BV.
www.iheartmypond.com