What's the difference between white light and blue light in an aquarium?

Question

I have a 12 gallon salt water tank that I'm just priming to get fish into. Do I need to run both the white and blue lights all the time during the day? I only have a few live rock in there now.

Answer 1

Actually, there's no good reason to run actinic light (the blue) all day other than some people think it makes their tank look better, or more like a natural underwater scene. The white light (probably a 8,000-10,000K) is the one that provides the wavelengths that the zooxanthellae need for photosynthesis.

See this website with forum answers from marine scientist and author Robert Fenner on this subject: http://www.wetwebmedia.com/marine/setup/lighting/actinicfaqs.htm

Since the white is a big jump in intensity from lights off to lights on, many reefkeepers will run only the actinics for an hour at the beginning and end of the photoperiod to simulate a dawn and dusk effect, so the lighting change is more gradual, with both on during the "daytime". Some "extremists" will use timers to turn the white tubes off at varying times to simulate "clouds" passing over.

Answer 2

The blue light is primarily for sea or salt water aquariums, and you can run it at night. During the mornings run the white light, as it creates more of a daylight atmosphere. In either cases, you can run them alternatively as there is no hard and fast rule on color and white lights.

Nemo

Answer 3

The Blue light or "actinic" light is primarily for the zooxanthelli algea that live in the tissues of corals, anemones, and clams. These algea are necessary for the coral's health. If you don't have corals or clams, You don't require actinic. But it does look good together with the white light. Jason (Phoenix Phish Care)