The image contains too much glare to provide an accurate identification.  If you still have the specimens saved then I recommend using the following key (https://wildlife.ohiodnr.gov/portals/wildlife/pdfs/public%20areas/OWCAtlas_WaterFleas.pdf). 

Here is the full citation...

Boehler, Jakob A., Tamara S. Keller, and Kenneth A. Krieger. 2012. Taxonomic atlas of the water fleas, “Cladocera” (Class Crustacea) recorded at the Old Woman Creek National Estuarine Research Reserve and State Nature Preserve, Ohio. Final report to Ohio Department of Natural Resources, Division of Wildlife, Columbus.

Hi Chris

Thank you very much for this! The Daphne are within a pond on a green roof in London.

Although not a clear picture, it certainly distinguishes the genus Daphnia.