INTRODUCTION TO MARINE MACROALGAEMacroalgae, or sometimes so called seaweed, seems to have become within the last years more and more popular amongst marine aquarium hobbyists. Previously macroalgae were often used specifically to provide a natural way to export the nutrients in the aquarium water, which means that the algae will grow by using compounds like nitrate, phosphate, ammonium and some heavy metals in the tank water. During this photosynthesis process, it uses carbon dioxide too and turns this into additional oxygen for the aquarium inhabitants. As well it will help to raise the pH level in the tank and increase the tank carbonate buffer capacity, which means are more stable alkalinity level. In addition, it is often used to provide additional hiding spaces for copepods and rotifers. Nowadays thanks to the variety of available macroalgae species, macroalgae can still fulfil these very important functions but they add a very important benefit too . . . . . . a beautiful and more natural looking tank.