[mesocosm]

Greetings All !

"Why do so many of us have difficulty growing chaeto until we l slap on a cheap incandescent light?"

Spectrum. Most "intended specifically for marine aquaria" lights generally have a spectra of 6500K to 10000K + . Chlorophytes (Green algae) typically prefer a spectrum closer to 5000K . But as has been said, there's more to it than light ... .


sfsuphysics,

"is there any word on color spectrum of the light which is preferable for macros?"

If you want to play in the land of serious macroalgae spectral data (... with coverage of both growth and reproductive correlations ...), I recommend "The Biology of Seaweeds" (Christopher Lobban & Michael Wynne, Blackwell Scientific Publications, 1981) ... great stuff, but requires effort to digest.

Such information is only now beginning to filter into the commonly available literature. IMO, "Reef Invertebrates. An Essential Guide to Selection, Care and Compatability" (Calfo & Fenner, 2003) presents the best information on the utilization of macroalgae and marine vascular plants available in mainstream hobbyist literature to date.

HTH.