Very nice Duanes!
A refugium can be a lot of different things, it depends what you want to accomplish. If nutrient export is the goal, then what is shown is great. If the goal is to provide a place for planktonic food as is common in a saltwater set up, then I would avoid shrimps and fish as they will eat what you are trying to provide to the main tank. At any rate in my opinion clams are a bad choice as they don't only use, but manufacture their own, waste products. In my salt fuge there is a deep sand bed and a few macro algaes that I regulary harvest, no animals have been purposely added.