Serious question about light

[rcreightonb]

What I get from all this, what I’ve seen and read is that if you provide enough par with only blue light to produce maximum coral growth, then there would be no advantage to adding white light other than aesthetics.

If you don’t have enough blue light to provide maximum growth by itself then adding in white light would probably be beneficial. This almost has to be the case as we’ve all seen that corals can grow with mostly white light and very little blue.

From what RedSea is saying it sounds like they’re claiming their lights can produce all the light the corals can possibly use for growth in the blue spectrum. Therefore turning on the white light would only be for looks.

 

[VintageReefer]

What I get from all this, what I’ve seen and read is that if you provide enough par with only blue light to produce maximum coral growth, then there would be no advantage to adding white light other than aesthetics.
——-> correct


If you don’t have enough blue light to provide maximum growth by itself then adding in white light would probably be beneficial. This almost has to be the case as we’ve all seen that corals can grow with mostly white light and very little blue.
——-> correct. And the reason from my understanding is that white is made up of all color spectrums, mixed together. Including blue. So by adding white, or running strong whitish light like from halides, you are adding blue. As it’s included in white. But you are also adding red spectrum which aids algae growth, along with all other colors


From what RedSea is saying it sounds like they’re claiming their lights can produce all the light the corals can possibly use for growth in the blue spectrum. Therefore turning on the white light would only be for looks.
—-> many modern led companies do this as well. Reefbreeders can do it, take a look at the pic with their layout. They use 88 leds spread out and 60 of them are covering the violet to blue range. radions can do it, and they make the blue model with “more blue”. Kessil makes the tuna blue models. These are all because with wide enough blue violet spectrum coverage with peaks in the right areas, we can fine tune what we light our corals with and give them exactly what they need. Whites, red, green channels are only added in to provide fine tuning so the owner can adjust their tank to their viewing pleasure, and to brighten it up

 

[Formulator]

Also I read that many of you say that with white coral colours look better. I don’t get it. When I put the white, the colours look much more pale, shine less. If I put blue at the maximum everything seem shine and colour of the corals look super bright/intense!

This is subjective and everyone has their own preference. Personally, I don’t like my tank to look like an alien planet out of Star Trek. I prefer it to look more like something you would see while snorkeling, with just a pinch more blue to give it a pop. I like the brighter feel that white light gives the room. It makes me energized and happy vs the darker almost sinister feel of all blue.

Again, its up to you what gives you the most pleasure. It is a hobby after all

 

[VintageReefer]

I will say photos i take of my tank with an orange filter provides color correction for the coral colors. However the trade off is the sandbed and rock come out significantly more blue than in person.

The coral colors are correct in the first photo. But in person it does not look like a bucket of blue paint was spilled on my sand

The true color of the tank in person is more like photo 2, however I have to tweak settings on the lights for the camera and filters to work properly

 

[dwarfseahorse]

I ran blue only for almost a year. Occasionally manually turning on white a few times a week but overall 95% of the year was blues and violet only

To this day my schedule is blue/royal blue/violet only. I use whites for photos but predominantly blue.

Corals get what they need, I’ve heard also when setting lights up to increase blues to desired par, then add white for viewing preference.

Blue only also reduces algae growth (as algae prefers red spectrum and white is made up of all colors including red)

while “unnatural” it makes those colors pop! I’ve done natural color with halides and t5 for years but have grown to like the crazy neon look

Sometimes I add a tiny bit of white to brighten things up and make a violet

 

[kilnakorr]

I found this conversation fascinating:


This link starts at the point where they start talking about how the spectrum of our reef lights compares to the spectrum of real life coral reefs.

Wierd as they say blue light is filtered out by the atmosphere, which obviously isn't true.

 

[ISpeakForTheSeas]

My question is, do the corals/fish needs that white spectrum to growth faster, healthier, better or just blue it’s fine? If so, in which ratio blue/white?

The short answer to this is - it depends. Some specimens of some species do best under white/full-spectrum light (which has blue light in it) while others do best under blue light (no other colors mixed in). The exact ratio that is best likely depends similarly on specific specimen and species. For the long-winded discussion on this, see my quote below.

The study below tested Acropora variabilis and Porites lutea harvested from 2-6 m deep at maintained 6 m deep; they compared dark (no light), full-spectrum (the control), and blue light settings at 200 μmol and 400 μmol (they tested full-spectrum at 800 μmol as well, but 400 μmol was the highest they could get the blue); they used a metal halide light with polycarbonate filters to control what spectrum the corals were being exposed to - the corals grew (calcified) fastest under the blue light, but there was more photosynthesis under the full-spectrum (white) light:

"The light to dark calcification ratios of A. variabilis under 400 μmol photons m−2 s−1 of control and blue light were 8.4 and 10.5, respectively; while lower ratios were observed in P. lutea (3.4 and 4.5). In both cases, calcification under blue light exceeds even these of the control"

Light Enhanced Calcification in Hermatypic Corals: New Insights from Light Spectral Responses

Light enhanced calcification (LEC) is a well-documented phenomenon in reef-building corals. The main mechanism proposed for LEC is that photosynthetic CO2 uptake by the algal symbionts elevates the pH and thus enhances calcification. We evaluated the role of light and of photosynthesis on...

www.frontiersin.org

So, under controlled PAR with metal halides, these shallow water corals grew faster under blue light than white, but but photosynthesis decreased drastically under blue light when compared to white.

To contrast with that, though, another study (using three different species of Acropora - A. tenuis, A. muricata, and A. intermedia at 100 μmol and 200 μmol [low numbers, I know] with LED's) compared different spectrums (the first link below) and found that the inclusion of some red light drastically increased the growth rate (the second link below; the green/yellow spectrum made a little bit of difference, but they didn't add much of it in with any of the three spectrums used; it may have made a bigger difference at higher intensities):

https://www.researchgate.net/figure/Light-spectra-composition-of-LEDs-used-in-the-current-study-A-PBR-400nm-purple-430nm_fig1_367478086

https://www.researchgate.net/figure/Specific-growth-rate-of-three-Acroporid-corals-under-different-light-spectra-Values-are_fig6_367478086

The actual study:

https://www.researchgate.net/publication/367478086_Effects_of_light_intensity_and_spectral_composition_on_the_growth_and_physiological_adaptation_of_Acroporid_corals

Another contrasting study - Stylophora pistillata from shallow (3 m) and deep (40 m) waters; the shallow specimens showed the highest photosynthesis rates under full-spectrum lighting, but the deepwater specimens showed the highest photosynthesis rates under blue lighting (sadly, they didn't measure growth rates, and the study only took place between March and April, so it was rather short, and results may have changed if the study had been longer).

The spectral quality of light is a key driver of photosynthesis and photoadaptation in Stylophora pistillata colonies from different depths in the Red Sea

SUMMARYDepth zonation on coral reefs is largely driven by the amount of downwelling, photosynthetically active radiation (PAR) that is absorbed by the symbiotic algae (zooxanthellae) of corals. The minimum light requirements of zooxanthellae are related to both the total intensity of downwelling...

journals.biologists.com

So, does blue light grow Acropora or other SPS faster than full-spectrum (white) light? It depends on the coral (both species and individual specimen), the location and depth/temperature the coral is from, what light the corals are photo-acclimated to (a shallow water coral growing under blue light in a hobbyist tank for 5 years is likely going to be acclimated to blue light despite its origins), year-round weather conditions (storms and such play a big role in determining what light is reaching the water), the clade of zooxanthellae they're using, etc.

Does the kind of light used (metal halide vs t5 vs LED, etc.) make a difference, or is it all in the spectrum, intensity, and photoperiod? I don't think we'll be able to answer this unless someone is able to make LED's with the exact same spectrum as those other types of lighting, but I'd guess any differences would be minimal.

So, lots of different things go into the growth, and again, fast growth doesn't necessarily equate to excellent health/coloration (it might, but it also might not). Does each coral species have it's own optimal spectrum for growth/health/color? Probably, but I doubt it would perfectly match a different species own optimal spectrum, so I don't know that it would much matter in our tanks - instead, we'd need to find the optimal spectrum for a broad range of corals, which may not be optimal for any particular coral we keep:

"Zooxanthellate corals display contrasting photoacclimation responses, coral cover, colony morphologies and genetic richness along depth gradients33,49,50,51,52,53,54, which collectively suggest that coral species occupy different light niches."

Photosynthetic usable energy explains vertical patterns of biodiversity in zooxanthellate corals - Scientific Reports

The biodiversity in coral reef ecosystems is distributed heterogeneously across spatial and temporal scales, being commonly influenced by biogeographic factors, habitat area and disturbance frequency. A potential association between gradients of usable energy and biodiversity patterns has...

www.nature.com

Personally, I'd expect to see similar (not the same, but similar) growth rates from a lot of corals under both blue and full-spectrum lights; some will likely do better under one than the other, but determining which is a lot of effort.

For that reason, like I've said before, at this point in time (barring a major, undeniable scientific breakthrough with our knowledge of corals and light), I would personally only suggest running the windex blue tanks if you really want to see the coral fluorescence pop (as mentioned by others, though, the colors may be best in the long run if you run different spectrums than just blue throughout the day). Like many others have mentioned in various forms by this point, I'd personally run a full-spectrum (white) light that leans somewhat more toward the blue side of things. Is that the "best" spectrum? Maybe, maybe not, but it seems like a good, safe place to start from.

With regards to fish, some have been found to need lighting from the other colors of the spectrum (green, yellow, and red specifically at this point) to develop healthy, mature reproductive organs (important for aquaculture, but not so much for the average hobbyist tank), and the lighting their under does play a role in long-term coloration. I suspect it plays a role in long-term health as well, but I haven't seen any long-term studies on the impact to say for sure.

Yeah, some things that can impact a fish's coloration (leaving a few irrelevant factors out of the conversation):
-Light (wavelength, intensity, and duration)
-Health
-Diet (including both vitamins, minerals, etc. and pigments like astaxanthin in a fish's diet)
-Various chemicals and hormones
-Genetics

Some things that affect a fish's coloration are immediate (like stress) while others (like lighting and diet) can take much, much longer to make a noticeable difference. It's possible that this tang's coloration is a result of some of those less-immediate factors, so it may take a while for it to change.

For an example of the difference that lighting can make:

Does Lighting Affect Your Fish

About 4 months ago I got 3 Captive Bred Goldflake Angels from Bali Aquarich. In the acclimation bucket one was slightly bigger than the other 2 and started kicking butt. So I tossed him into one of the outdoor frag tanks. The other 2 went into the 750g display tank. One that went into the 750...

www.reef2reef.com

With regards to blue/white light and algae - it's possible (but seemingly unlikely) that running just blue light offers a very small, competitive edge to (some) corals instead of (some) algae. For another long-winded discussion on why, see the quotes below.

I haven't gone looking too much into the specifics of algal growth under various light conditions at this point, but oreo54's post on page 1 here gives some idea of the complexities involved with this discussion/research (i.e. what the "white" in the light itself is, the kind of algae involved, etc.). That said, from what I've found, there are currently only two things I've come across that are scientifically researched that seem to possibly support the idea that lowering "white light" and/or running just blue light decreases algal growth (and one of them I'd feel a lot more confident about the assertion that it might lead to a decreased amount of algae if Randy thinks there a chance it would be impactful/meaningful from the chemistry side of things):

1 ) Most algae use Chlorophyll A and some other kind of Chlorophyll (B, C, or D), while corals basically use just Chlorophyll A (this is an extreme simplification - there are a number of other important pigments involved as well, and some corals technically use a little Chlorophyll C as well); in theory, by hitting just the spectrum for Chlorophyll A by using just blue light, it could potentially provide corals an edge over the algae (I haven't seen studies done on if it actually does provide an edge or not though, and I would assume any edge given is small).

2 ) This is the one where I don't know enough about the chemistry involved yet to know for sure if it would even matter, but:

Corals will still grow under just blue light, yes. As mentioned, changing from white and blue or just white to just blue will likely impact the coral's growth, coloration, and possibly health (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).* Switching to blue light from white or white/blue will also impact any photosynthesis going on in the tank:

"More importantly, under blue light calcification is very high, even higher than under full spectrum, while photosynthesis remains below the compensation point, meaning that CO2 production is higher than consumption (Figure 4B)." **

*Source:

Green fluorescent protein-like pigments optimise the internal light environment in symbiotic reef-building corals

Scalar irradiance microsensor measurements performed inside the tissue of living corals show that absorption and fluorescence emission by host pigments produce dramatic spectral alterations in the light environment experienced by the symbionts.

elifesciences.org

**Source:

Light Enhanced Calcification in Hermatypic Corals: New Insights from Light Spectral Responses

Light enhanced calcification (LEC) is a well-documented phenomenon in reef-building corals. The main mechanism proposed for LEC is that photosynthetic CO2 uptake by the algal symbionts elevates the pH and thus enhances calcification. We evaluated the role of light and of photosynthesis on...

www.frontiersin.org

***This third link reinforces both of the points listed with the other links:

The spectral quality of light is a key driver of photosynthesis and photoadaptation in Stylophora pistillata colonies from different depths in the Red Sea

SUMMARYDepth zonation on coral reefs is largely driven by the amount of downwelling, photosynthetically active radiation (PAR) that is absorbed by the symbiotic algae (zooxanthellae) of corals. The minimum light requirements of zooxanthellae are related to both the total intensity of downwelling...

journals.biologists.com

In my mind, photosynthesis remaining below the compensation point could potentially mean that the blue lighting rather than white lighting helps limit algae by reducing available oxygen in the tank, but - again - I'd run this one by Randy to see if it might be valid.
(P.S. the quote above is - I'd imagine - why many big coral sellers run full blue lighting: maximizing coral growth; importantly, however, as noted, this maximized growth under blue light may only apply to deeper-water corals.)

Anyway, as mentioned, there's also a chance that lowering PAR by decreasing the white channel on your lighting could also decrease the amount of algal growth simply by limiting the potential energy uptake of the algae.

So, there are a few things that indicate that decreasing white lighting could potentially reduce algal growth, but whether it actually would reduce it or not has - to my knowledge - not actually been studied at this point.

Regardless, at this point in time, since there's not really any solid evidence that running just blue reduces algae growth, I'd suggest it may be better to decide if you want white lighting or blue lighting based on 1 ) whether your corals are from deep water or shallow water, and/or 2 ) if you want your coral fluorescence to really pop or if you want to be able to see your fish/other inhabitants' colors better.

Some other, pertinent information:

From what I've read, it's because algae generally uses different light wavelengths for photosynthesis than coral zooxanthellae do - corals using more blue light, and algae using more red and green/yellow.
For a simple explanation, here's a graph from Khan Academy about photosynthesis and light absorption:

I wish I could find the graphs that I've seen specifically for corals/algae, but I can't remember where I've seen them. Anyway, basically the "Windex" blue light tanks use that spectrum (and some people recommend it over using white/red lights) because - at least theoretically - the corals do fine using primarily the Chlorophyll A provided by the deep blue while essentially starving out the algae by not providing the green/yellow and red lights for Chlorophyll B and Beta Carotene. I've seen some more complicated charts of this with more absorbing pigments than just these three (Chlorophyll C, Chlorophyll D, PSC, and PPC to name a few), but - again - I can't find the ones I've seen for corals which would be more useful, and this one gets the point across.

So, the theory is that you feed the corals with blue light, and the algae with other lights. By reducing the other lights, you stop feeding the algae/give the corals the competitive edge. That's why people say to reduce intensity of other colors to stop algae. How accurate that theory is would likely depend on the specific corals and algae involved, but the theory seems relatively sound when speaking broadly. Since many (possibly most) algae species utilize Chlorophyll A, I have no idea if it's effective or not, but there is a chance that it gives corals the edge they need to beat out algae. I'm not aware of any studies that actually show one way or the other though.

With regards to the "... old ones grow algae!" - here's a quote from Dana Riddle on it that basically says it's possible following the same lines of reasoning listed above, but he's not (or at least wasn't) sure if it was true:

I hope others will chime in here - It has been a axiom in the hobby for years that degradation of spectral qualities in certain lamps (fluorescents, metal halides) will encourage certain algae to grow. The reasoning is usually that the lamp becomes 'more red' (suggesting the total amount of red increases) which gives me some heartburn - the lamps often becomes less blue and the percentage of red increases. The difficulty (for me at least) is separating intensity from spectrum. It is true that chromatic adaptation can occur, but I'm not at all sure preferential growths will occur. My focus for years has been responses of zooxanthellae to light intensity and how it might affect coral growth, so responses of green, brown, and red algae are a bit out of my field (although there is no doubt that their absorbance qualities differ.) Anyone - ideas, suggestions?

In case you're curious, here's a graph from the paper linked below that shows different classes of algae use different spectrums of light for their photosynthesis:

https://www.researchgate.net/publication/333210678_Algal_Biofuels_Current_Status_and_Key_Challenges

Yeah. That’s why I said that it’s possible it gives corals the edge, but - personally speaking - I doubt it’s a big enough edge to make a meaningful difference for most algae (and, personally, it’s not something I’d “Windex” a tank for). That’s why people suggest it though. Personally, I’d say that if you’re going to turn your tank blue, you should do it for the fluorescence, not for algae control, but that’s just me.

Some people believe that by only using blue lighting, they will limit algae growth/give coral an edge to outcompete algae. I find these claims to be pretty dubious personally, as most algae species utilize blue light as well, but it's possible there may be some small anti-algal/pro-coral effects.

I have a couple of posts on the thread linked below* discussing using blue lighting for algae control that go into a bit more detail, but - to be brief - using lighting to control algae doesn't seem to be anywhere near as effective as many people make it out to be. It may help limit a few types of algae, but I personally wouldn't run all blue lighting to try and prevent algae - if I was going to run all blue lighting, it would be to get a good fluorescent pop from my corals.

* The thread: https://www.reef2reef.com/threads/w...olor-here-to-stop-algae.919937/#post-10338958

I haven't looked much into the tail ends of the spectrum, but a few people swear by infrared lighting as being beneficial to corals, and I know that UVA lighting does have a positive impact on the fecundity of at least a few animals (such as Ghost/Grass Shrimp). So, while the tail ends of the spectrum may not be needed, there may still be some benefit in providing them for your tank regardless.

 

[Phish Stix]

See a lot about wavelengths in these articles, what about par levels and for what length of time. I have a 72in by 30in deep. Top level of SPS coral at 10in below water line, and 18 inches from lights (3x X30 Pro), PAR is at 250 at peak of photo period for two hours (13 hours total). I maintain 175-200 PAR at the outer edges of the photo period. Start with 3 hours of blue, 6 hours of mixing in WW and some CW, and ends with 3 hours of blue. I have another layer of SPS 10 inches below the first layer at top of rock scape. The PAR at best for those SPS 160 - 175.

I have been cutting back on the white and adding more blue over time as even at those PAR levels SPS coral were getting bleached.

The question, what is everyone keeping their PAR levels at for SPS and for how long? Top and middle of tank?