Sea anemones share a clade with corals and require similar lighting. Sea anemones and coral host symbiotic algae within their cells. This algae, called zooxanthellae, provide the anemone with energy in exchange for carbon and nitrogen. Anemones need powerful lighting to support their algal symbiotes.
How Much Lighting
Most of the time, aquarium lighting is measured in terms of watts of light power per gallon of aquarium capacity. The usual guidelines is that anemones and other photosynthetic reef organisms need at least 5 watts per gallon. However, deeper tanks will need more powerful lighting than this. At the same time, you can "cheat" by putting light-hungry anemones in the upper reaches of the aquarium to get more powerful light.
Traditional Reef Lighting
Usually, reef-style aquariums -- those that accommodate invertebrates, like sea anemones -- use various high output (HO) or very high output (VHO) type of aquarium lights. This includes advanced types of fluorescent lighting, like T5 lights and powered compact tubes. These advanced lights need special fixtures above and beyond standard aquarium fluorescent lighting. Metal halide bulbs also are popular. These bulbs produce light strong enough to penetrate deeper into aquarium water, making them ideal for deep aquariums. Many types of high-output aquarium lights need cooling fans to avoid dangerously heating the aquarium.
You also can light your anemones with LED arrays, which are the new game in town for advanced aquarium lighting. They can be more expensive up front, but their initial cost is dropping as the technology matures. At the same time, they cost less to run, since fluorescent tubes and metal halide bulbs must be replaced yearly, while LEDs may last longer than 10 years. At the same time, LEDs take about a fifth of the electricity to get the same output as a metal halide. The biggest downside is the watts-per-gallon rule doesn't work with LEDs, who's output is better measured in PAR. Most commercial LED arrays include charts to decide how much light you need in terms of PAR.
While anemones get most of their energy from light, all species also benefit from live feedings. Most species will thrive better, and may reproduce more when fed. Feed meaty foods once or twice a week. Grocery store sea food makes a great food for anemones. Place a small piece of squid, fish or shrimp in your anemone's tentacles and it will move it rapidly to its mouth.
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