The photo isn't clear enough to show the detail necessary identify them. It is a challenge to photograph something so small without specialized equipment. From a vague sense of the shape and size, and the description that they float to the surface, my first guess would be springtails. Perhaps if you can search for a photo of white springtails you can see enough detail by eye to make a match. Springtails do not all look alike so you may have to look at more than a few pictures to find a match.