740nm

Sunny Goold · Aug 3, 2020

Hi Dana - watched the @ReefBum rappin episode and I loved it!

Thanks so much - super helpful.

This is just for interest (I have my lights for now) But I feel like I saw someone (maybe you) mention that 740nm helps corals (SPS) protect itself from too much light.

So if that is true - I assumed (wrongly maybe) that it would be good to have some 740nm diodes.

My question is - is 740nm helpful?

I think the older Orpheks had 740nm and have now gone to something like 840nm (I wonder why). In the future I'd like to get Reefi and add some custom bars (maybe Orphek) - mainly blue with some 380ish and 740s added in - plus some Cyan more for the pop I heard the new Radion Blues deliver.

But it's just a general question really for interest and to see if I am thinking in the right direction

Also sorry to hear about your issues after the move (again). I left dry rock in a tank with a couple of small pieces of LR and a wrasse for a year before I put it in my new tank - still have a couple of aptasia but I think for sure it's worth it (I have clams and think a Copperband would be fine and a great fish but don't think it's worth it). Thanks for everything you do for the hobby Dana

I find it super helpful.

Dana Riddle · Aug 3, 2020

Here's the low down on 740nm radiation. There are two Photosystems - Photosystem One and Two. Photosystem Two's reaction centers contain a pigment that absorbs light maximally at 680nm. The reaction center in Photosystem One contains a pigment that absorbs light maximally at 700nm. In a quirk of scientific nomenclature, Photosystem Two first collects light and transfers it to Photosystem One (named since it was discovered first.) If Photosystem Two collects too much energy, selective stimulation of Photosystem One helps drain energy from Photosystem Two, thus 740nm radiation collected by Pigment 700 helps some in preventing damage to the photosynthetic apparatus. I am uncertain of any benefit of 840nm radiation. And thank you for the compliment!

Sunny Goold · Aug 4, 2020

Ahhh thank you. That is a super cool mechanism and now I think I understand why I was confused by Red light is bad... because Red LED diodes are typically below 680nm (660 comes to mind) and so that red is narrow and damaging - but if the red diodes were more 700+ (maybe that is towards near-infrared) then you would have less chance of bleaching.
I suspect that is a secondary answer to @gcarroll awesome question on halides not bleaching - that halides have a much broader spectrum and would hit that 740nm so the corals are able to use that mechanism.
On the more green in halides (main answer) that was super helpful to me. I have SB Reef Lights and they focus on 450 and 420 - but I have an extra 470nm bar I manually turn on at night, when I am home, and I typically run it later - my thinking was that as that isn't absorbed like the 450nm so it's giving me nice viewing and pop without giving the corals too much extra photons.
Thanks for the explanation - I love hearing about the why and then thinking about the implications - to me it's super interesting. It does make me wonder why LEDs have 660 diodes and don't go higher or add 740 but I guess its the visuals and dimness of that wavelength range.
Thanks so much!