Personally i have found that my cherry shrimps virtually swarm snow (or mulberry leaves, zucchini and most other processed foods too) when i put them in the tank. As such i only put in enough food for them to finish within a few hours at the most with the exception of snow and barley straw which will last for a while longer but shrimp still demolish them within a day or so... I recall someone (shrimpydaddy i think) saying that shrimp swarming food was a sign that the tank is over-grazed. I'd