White Lighting As It Pertains To Algae

[vetteguy53081]

I'm currently scouring the interweb looking for any sort of study and cannot find much. Aside from reefing forums/articles written by various unconfirmed people, I can't find any proof that lowering/shutting off your white channel effects algae growth. Leading me to believe that this is nothing more than an urban legend passed around the reefing community

Hang on for @Dana Riddle
I tagged him already and he is our lighting expert

 

[ptrick21186]

I'm not sure if that logic is sound. Corals and algae both use Chlorophyll A. So if you use the spectrum of light that activates Chlorophyll A you can somehow feed coral while starving algae? Even though they both use the same Chlorophyll A?



Regarding the absorption spectra of various photosynthetic pigments; I deeply enjoyed this thread recently. It raises some very thought-provoking points about green light in particular.

https://www.reef2reef.com/threads/a...photosynthetic-organisms-in-our-tanks.567285/

I'm definitely gonna have to check out this thread when I got some time

 

[ISpeakForTheSeas]

I'm not sure if that logic is sound. Corals and algae both use Chlorophyll A. So if you use the spectrum of light that activates Chlorophyll A you can somehow feed coral while starving algae? Even though they both use the same Chlorophyll A?

Not quite; the thought process is that if the coral only uses Chlorophyll A (again, a gross simplification) while the algae uses Chlorophyll A and - for example - Chlorophyll D, then by not providing light for the Chlorophyll D, it'll slow the algae growth down marginally, thereby providing an edge for the coral (not starving the algae/preventing it from growing, but basically reducing the extra "nutrition" that it would be provided by the Chlorophyll D so that it grows more slowly, if that makes sense).

To put it another way, there's a chance that the other Chlorophylls utilized by algae are important enough to their growth rates that by depriving them of those other Chlorophylls, they will grow slower than corals being given their preferred Chlorophyll. Personally, I find it doubtful, but that's the thought process on it.

 

[Erasmus Crowley]

Not quite; the thought process is that if the coral only uses Chlorophyll A (again, a gross simplification) while the algae uses Chlorophyll A and - for example - Chlorophyll D, then by not providing light for the Chlorophyll D, it'll slow the algae growth down marginally, thereby providing an edge for the coral (not starving the algae/preventing it from growing, but basically reducing the "nutrition" that it would be provided by the Chlorophyll D so that it grows more slowly, if that makes sense).

To put it another way, there's a chance that the other Chlorophylls utilized by algae are important enough to their growth rates that by depriving them of those other Chlorophylls, they will grow slower than corals being given their preferred Chlorophyll. Personally, I find it doubtful, but that's the thought process on it.

Okay. I can see the logic in that.

However, that theory assumes that coral can get a higher percentage of their metabolic energy from Chlorophyll A than algae is capable of, and I don't think there is any evidence of that. It could just as easily work the other way around, and you could end up with the coral suffering more than the algae does. If that happened, then the algae would outcompete the coral for nutrients and territory even faster.

 

[ISpeakForTheSeas]

However, that theory assumes that coral can get a higher percentage of their metabolic energy from Chlorophyll A than algae is capable of, and I don't think there is any evidence of that.

I haven't seen any evidence for this either, and - like I said - I find it doubtful.

It could just as easily work the other way around, and you could end up with the coral suffering more than the algae does, leading to coral decline. Then, when you turn the lights back up for the coral's benefit, the algae is in a more dominant position than it was when you started.

Yeah, this is part of what I was getting at with the deep water/shallow water coral comment about my first quote:

importantly, however, as noted, this maximized growth under blue light may only apply to deeper-water corals.)

The relevant part of my first quote:

(if the coral is from deep water rather than shallow water, using just blue light will likely increase coral growth and health - if the coral is from shallow water, switching to just blue may decrease the growth and health).*

 

[teaktoc]

I tend to disagree heavily that white light causes algae. Yes, it can, but that is dangerously misleading.

Algae thrives on light and nutrients. Same as all photosynthetic marine organisms.
By extension, yes white light feeds algae. But, if your tank is conducive to algae growth, solid blue light of equal par levels will grow it just as well. You just can’t see it very well.

Personal opinion here: People promote blue heavy light as a means to fight green algae. When in reality, you’re simply eliminating the visible wavelengths needed to reflect the color of the algae. Algae contains chlorophyll. Algae absorbs that big fat blue “bio band” for growth just as well as corals.

As mentioned above, a mature tank with stable parameters, plentiful herbivores, and well occupied rock space with desirable organisms will help fight algae plagues. But really, marine algae, aiptasia, fungus, pathogenic bacteria, and mean predatory crustaceans, are all every bit as natural and normal parts of the ecosystem as the most desirable torch coral or sps frag. I find it helpful to keep that in perspective.

Here’s a picture of my tank started with dry rock at the one year mark. Nutrients in stratosphere and wildly fluctuating parameters. A young volatile tank.

Lights pushing 400-500 par. Kessils set full white intensity. Red channel up at 70%, green channel at 80%. How is it I have no turf algae swallowing up the rock? Rabbitfish, tangs, a few massive turbo snails and literally
About 500+ cerith and dwarf cerith snails.

Algae is more a product of poorly stocked herbivores than it is too much white light.

Exactly as it nature intended.