I work with larger amounts of conditioned media (30ml at a time, 180ml total) and my pellet is very hard to see as well.
I find that I can see my pellet by holding the tube up in the light and looking for a raised bump on the surface. Often by pellet has a brown tinge, which disappears after a PBS wash.
I spin media at 100,000 x g but for 90 min, and my pellet does not easy wash off the side of the tube. I scraped it with a pipette tip when I resuspend it.