Surge is the back and forth movement one often imagines when one thinks of a reef. As the waves move into shallow water the circular motion of the water becomes compressed and flattened, causing the water to move back and forth. This is best demonstrated by the to and fro motion of large sea fans in shallow reef areas. Surge is an important factor in the ecology of many reef organisms, especially flexible ones. The back and forth movement exposes more of the surface area to light, increases the feeding efficiency of polyps and greatly helps in the exchange of metabolites and gases with the water.
Turbulence is a random swirling of water in all directions.
This is often caused by opposite currents clashing or water swirling around objects. Laminar flow is water movement in one direction and is the type of flow commonly generated by aquarium pumps and encountered on deeper portions of the reef. When it comes to keeping reef organisms we must take into account the area from which they were collected, since this will determine which forms of water movement they are adapted to. I cannot stress enough the importance of proper water flow in any marine aquarium. I remember when I was a teenager, there was a store I used to frequent that specialized in marines.