Sunlite Science and Technology

Problems with Metal halides:
1. Less efficient
2. Get very hot, need small fan to flow air across the lamps, and sometimes a chiller
3. Many metal halides require a 100-200 hour burning in period until their true color comes out. So the color of a new bulb may be significantly different than the color of the bulb it replaced so this should be kept in mind when bulbs are replaced.

Problem with fluorescent blue:
1. Color spectrum of a lamp changes as it ages, will cause outbreak of algae growth.
2. Produce less light over time,
3. Linear fluorescent tubes should be changed out every six months and compact fluorescents every year.

The wavelength
For green plants the lighting absorption peaks that are most important:
1. Chlorophyll-a: 430nm/662nm
2. Chlorophyll-b: 453nm/642nm
3. Carotenoids: 449nm/475nm

Blue light (~475nm): optimize plant leaf development, penetrates water better and more quickly than red
Red light (~625nm): stem elongation and color, is more efficient than blue

Green algae uses the same light as plants
Blue-green algae (cyanobacteria), absorbs light in the low 600nm

Plants are able to start photosynthesis once there is sufficient light.
Algae need a long and uninterrupted lighting period to function properly.

Lighting length
6-12 hours for fish only tank;
10-12 hours for plants and reef tank;
more than 10-12 hours per day will cause algae blooms;

Please see the attached file for more details