Macro Algae

Mention the word ALGAE to any aquarist, and you will most likely conjure visions of the dreaded hair algae, or Heaven forbids, slime algae. Fortunately for marine aquarists, these primitive plants also have some beautiful and beneficial, cousins, the so-called Higher Order, or (Macro) algae.

I will not delve into the structure or identification of these plants, as I'm not a biologist or a botanist. However, from observations in my own tank, and by using some common sense, the following is quite obvious:

Macro algae compete with the nuisance algae (such as nitrates and phosphates) as food . Having a good quantity of macro algae in your tank will thus inhibit the proliferation of the unwanted "nuisance" algae.
The faster growing types, such as some Caulerpa species, can be used to actively export nitrate and phosphate "pollutants" if you harvest and removing some of the growth on a regular basis.
Macro algae are an important food source to many herbivorous fish, such as Tangs.
Many green, red and brown algae are beautiful to look at, and give a much more natural look to your tank.
The faster growing Caulerpa species can sometimes die back suddenly (probably due to a lack of nutrients, such as iron), releasing a large amount of organic matter into the water. This could cause blooms of unwanted "nuisance" algae.
Macro algae could also shade your corals, thus depriving them of essential light. Regular "pruning" can prevent this problem and the problem of sudden die-off.