3 of my 4 shrimp tanks are breeding really well right now, and are full of shrimp... I have a few orange ones in a 4th tank, and haven't hit the right combination of shrimp yet in that tank... last night when I took these pictures, there was only one orange shrimp on that feeder block, so I didn't take a picture of that one...
When I put a piece of lettuce, cabbage apple or cucumber in my tanks. it does attract both shrimp and snails. I've used calcium feeders as well in the past but I just didn't want to buy them so often. And veggies are something I have around every day overhere.