Macroalgae are commonly often just called seaweed. Although a lot of macroalgae species are edible we offer for sale all macroalgae species just for the use in the marine aquarium, so don't be tempted by the great pictures, please.

Macroalgae species are divided into three main live algae species groups which are the red macroalgae, green macroalgae and brown macroalgae.

The most common and widely available macroalgae species are the green marine algae species. Especially the different varieties of Caulerpa are widely available as they often grow very fast and are easy to keep. They are successfully used to reduce the Nitrate and Phosphate level in the aquarium water, which can help to suppress nuisance microalgae.
The only downfall with green macroalgae species is that they are often invasive, which means that they can overgrow your rockwork when not kept under control. Often they are placed in a Refugium / Sump to let them do the nutrients export work and to keep them in a controlled area.

The second biggest group are the red macroalgae species, which often grow much slower than the green marine algae species, which means that they take less nutrients ( Nitrate / Phosphate ) out of the water but therefore they add some beautiful colours to the marine aquarium and in our opinion, some species are so good looking that they can easily compete with harder to keep coral species.
But the best they are often non-invasive and therefore just perfect to be placed in the Display Tank.

The third largest macroalgae group are the brown macroalgae species, which are very rare to get, as they are not very often used, and more often seen as unwanted macroalgae in the marine aquarium