Water movement is one of the most important topics in marine aquaristics. Creating the perfect water circulation requires knowledge and understanding of the needs of a saltwater aquarium.

Waterflow plays a number of key roles, it’s extremely important in gas exchange (the better the circulation, the better the pH in the aquarium). Proper circulation provides food for our micro life and corals. The correct water movement keeps our tank clean. Importantly, thanks to the appropriate water flow, corals are able to cleanse themselves of metabolic waste and even parasites. Corals produce a mucous coating that protects them, so when the water flow in the aquarium is too weak, the coating can become too thick and excess detritus can get stuck in it, which in turn can cause various types of infection in the corals. Last but not least, water circulation also affects the process of nitrification and denitrification. 

The movement of water in the tank can be neither too weak nor too strong, so how to set the right circulation? That’s what I’m going to show you in this article.

Types of water movement

At the very beginning, it is worth taking a look at the types of waterflow that occur both in nature and in a marine aquarium. We distinguish: waves, eddies of water in different directions, movement of water in one direction.

Each of these water movements has its benefits for the corals, and in the aquarium they can play a specific role. Waves make it easier for corals to pick up food from the water, spontaneous swirls will allow corals to clean themselves more easily, and directional flow allows the aquarium to get rid of dirt by directing it to the chimney.

Tips for circulating water in your tank

Now that we understand what types of circulation exist and how they affect the corals and aquarium, it will be easier for us to set the right waterflow.

The ideal solution would be to program the circulation to be variable and able to simulate all types of water movement (with variable force).

In our company, I am in the process of developing a comprehensive solution that will allow this type of simulation.

If you do not have the option of setting variable circulation, then my suggestion is that you create a constant current of water, aimed at cleaning the aquarium from dirt. Place the circulators so that the final movement of the water is directed to the chimney.

The figure you see above shows how to properly set up continuous flow circulation to clean the aquarium of dirt. The rock is in the middle, the circulators are set so that the water creates a circulation around the rock and finally the stream of water blows the dirt into the chimney. Water from the chimney will get into the sump, where the biggest dirt will be removed, for example, with a filter sock, cotton wool, or automatic Smart roller or roller mat filters. Such a setup is recommended for beginners, because in a simple way we can effectively set the water current so that there are no dead zones in the aquarium and impurities are easily removed from the main tank.

Creating a wave is quite simple, but it requires a special program on the circulators, which will allow you to switch them on alternately, so as to cause waves.

Spontaneous vortices are a more difficult topic. One way is to aim the circulators directly in front of each other. Water collisions will cause various spontaneous vortices. Another way is to aim the circulators at the aquarium glass, so that the water bounces back, creating vortices.