Viv V, my new giant Lagoon Ecosystem Vivarium is complete. This giant tank simulates a brackish habitat where a beach meets a mangrove forest, tidepools, jungle, and oceanic lagoon, offering a variety of ecological niches for many animals, macroalgae, and more. But what makes this tank more than just your average saltwater aquarium is the rising and falling of tides, but getting it to work, was the challenge.