Cultivate the "Right" Kind of Algae
Algae are photosynthetic life forms lacking specialized cells typical of true plants (i.e. vascular structures, leaves, and roots). Algae can multiply rapidly as long as their basic needs are met. They are highly adaptable and thrive almost anywhere with a light source and an abundant source of nutrients – both present in many marine aquariums. Due to their success, most algae grow to nuisance proportions rapidly, spreading stubbornly as you watch helplessly.
Macro Versus Micro
Many hobbyists are now taking advantage of the efficient nutrient exporting ability of algae and are purposely cultivating certain types of macroalgae to help improve saltwater quality as well as combat less desirable species of microalgae. Macroalgae are large beneficial algae that actively utilize harmful ammonia, host beneficial microbes that improve biological filtration, and serve as a food source for fish. Some macroalgae, because of their beauty, also make attractive décor.
Cultivating "Good" Algae
Select species of macroalgae, such as Chaetomorpha sp. are grown in specialized areas of the sump or in refugiums. Refugiums are a great place to establish macroalgae since they are protected from hungry herbivores and are easier to manage. Macroalgae growth is contained in the refugium and excess growth can be easily clipped as necessary. The clippings can be fed to herbivorous fish. This process prevents macroalgae from aggressively spreading in your main display.
Since most sumps or refugiums converted for macroalgae growth (also known as "algae scrubbers") are located underneath the main aquarium, it is important to provide a separate light source for the macroalgae. A fluorescent strip light on for 10-14 hours a day provides sufficient light without encouraging over-aggressive growth.
The use of a timer automates the light schedule to make it easier to regulate the proper photoperiod. If you have plants in your main aquarium, run the lights above the algae scrubber on a reverse schedule of the main aquarium lighting. The staggered lighting schedule provides the added benefit of stabilizing pH and maintaining a higher oxygen level at night.
The careful cultivation of macroalgae harnesses the power of nature to prevent the growth of more noxious forms of algae as well as maintaining a healthy and stable aquarium.