Austria's Green Lake in the Hochschwab Mountains is a hiking trail in the winter. However, when the snow quickly melts in early summer it creates a completely clear lake. The lake has a grassy bottom, complete with underwater trails, park benches, and bridges to explore.
Light provides energy for plants, the plants provide food for the shrimp, and the waste from the shrimp feeds bacteria living in the substrate. The biological waste from the bacteria fertilizes the plants, which completes and renews the life cycle. The only input needed is a bit of sun, and an occasional top-up of water to make up for evaporation. No feeding is necessary!