Charles Delbeek's (Steinhart Aquarium) presentation at E-Reef Conference 2020. One of the key components of marine aquaria is water motion. A coral reef is a dynamic, high energy environment with vast amounts of water being passed over and through this environment. Sessile organisms such as corals and anemones rely on this movement of water to bring nutrients, carry away waste products and to spread offspring. Fish also rely on water motion to disperse off-spring and many are designed to live in a variety of water flow regimes; without proper water flow, many fish simply do not behave normally or thrive. This presentation will focus on the role water motion plays in coral and fish health, explore the various types of water motion and examine the tell-tale signs of inadequate water motion. The last two decades have seen a marked improvement in the quality and capability of water motion generating devices and we will examine the history of water motion devices and some of the recent developments in the area.