From your description I'd be inclined towards springtails which come in a sorts of shapes and colors. They should not be a problem for your plants. They eat decaying matter in the soil so massive amount may indicate your peat moss is breaking down.
Drowning them is likely to be ineffective in eliminating them as they are small enough to float happily on the surface tension of water without getting the least bit wet. Indeed massive colonies of them con be found floating on water.