The pinks take a while to get going, but once you have a nice start, they reproduce very nicely. Perhaps you just need to up your culture size to a plastic shoebox size. Mine do great in those cultured on charcoal and fed active yeast. Also, it should be noted that the Pinks seem to establish better than most inside your viv. When I seed several different types, two months later the pinks have a definite foothold over the other types. This has made the pinks my favorite choice. If I could only culture one type (God forbid!) it would be the Pinks.
A note on the blues. I was given a start of blues in a microfauna trade a couple of months ago. The original grower uses a VERY wet media. Looks like basically potting soil. He keeps pools of water at the bottom so we are talking TOTALLY SATURATED. While I intend to experiment with different medias, I certainly won't deny that they thrive in the very wet conditions.