This is some information for people not familiar with filter feeding shrimp. The easy way to tell if your filter feeders are getting enough food, watch for scavenging. They will take their fans and scrape them against rocks/glass or what ever, instead of holding them open in the water, there may be a problem. If you see this behavior once in a while it's not necessarily bad. Some just like to. But if they habitually do this, or if all of your filter feeding shrimp do it, then they may need supplemental feeding, or even more importantly, higher volume of water stirred in the tank.