The Diamon is 2 microns while the Dolphin is 20 micron - this is not something you can see the difference on with your eyes. I forget, but I think a human hair is about 50 microns wide. So, you would be hard pressed to be able to see the difference with a naked eye. But, a 2 micron bag will remove many tiny particles that scatter light in your pool water and removing them will make the water look noticeably clearer.