best spectrum for reef tank

[Ztrain]

So the cooler spectrum grows coral better?

 

[Dana Riddle]

Red light is most efficient - that spectrum is not even close to the absorption spectrum of protective xanthophylls. PAM fluorometry experiments showed photochemistry was highest in red light and naturally the xanthophyll cycle was at a low point (when photochemistry is high, the xanthophyll cycle must be low and vice versa.) But there is an issue - red light regulates zoox density and/or chlorophyll content. A "little" red light is good, at least in the zoox clade (C15) found in Porites corals. It is possible that the xanthophyll pool is at a low concentration/non-existent in coral zoox clades from deeper water, thus offering no protection from excessive intensity of light (red or blue.) In other words, the jury is still out - too much research needs to be conducted before broad statements can be made.

 

[tigé21v]

410 nm is moving away from the absorption peaks of protective pigments (diadinoxanthin & diatoxanthin) so naturally these wavelengths have a better chance in being used in photochemistry. If we look at the absorption curves of chlorophylls a and c2 (found within zooxanthellate), we see shortwave ultraviolet radiation can be used in photosynthesis. Protective pigments (Mycosporine-like amino acids, or MAAs) don't provide any protection against UV until around 350nm and below. There's a good reason for this - some UV wavelengths are used in photochemistry, so some of the UV LEDs provide more than the 'pop' (I hate that term) to coral fluorescence.

This stuff is so interesting... And so far over my head.
So, are you saying UV is necessary (or at least beneficial) to coral growth? If so, does it play a larger role in different coral species (SPS, LPS, Softies)? Regarding T5 lighting, would it be beneficial to add a bulb to the mix with more UVA and UVB than even a top-of-the-line actinic bulb provides?
And, if a UVA/UVB -heavy bulb were used, would it be better to run said bulb the entire photoperiod, or for only part?

 

[North Borders]

Bulk Reef Supply has done some awesome videos on lighting options and had some pretty in depth videos on spectrum. I would find you the links, but at work at the moment :/

 

[Justin Aretz]

Bulk Reef Supply has done some awesome videos on lighting options and had some pretty in depth videos on spectrum. I would find you the links, but at work at the moment :/

Link us when you get a moment!