Can I keep a mixed reef at 6500k lighting?

[Reefering1]

Both Phoenix 14 and Radium 20k have their roots in general purpose lighting. They renamed them for the reefing hobby once people started to use them over fish tank... and like them.

I live in Cape coral, fl. The "midpoint bridge", connecting the Cape to ft myers, was fitted with these beautiful blueish/ white light street lamps a couple years ago; they said it was a mix up, people spoke out to keep them... I swear those bulbs would suit a reef tank very well. I wish I had a pic to share

 

[Miami Reef]

If anybody thinks that any of this is a joke, search around for frags coming from really good vendors, like BattleCorals, where they are grown and raised with a lot of full-spectrum lighting. They look really good at first and then the colors fade when they are kept under heavy blues only and they lose some color over time. This is a common thing. Easy to sell these folks on more daylight trips to the gym, good diet and some sunscreen or other skin care.

Every time I read your posts about lighting, I try to make my tank whiter, but I don’t like it. I understand that corals would grow and look better with whiter lights, but it just makes me not like the tank.

I have 5 blue plus and 3 coral plus.

I just traded a blue plus for an aqua blue special and I don’t like it very much.

 

[Reefering1]

And that shimmer..........

I think that's the hypnotist's pendulum that gets you stuck like a moth in the light

 

[Reefering1]

Every time I read your posts about lighting, I try to make my tank whiter, but I absolutely hate it. I understand that corals would grow and look better with whiter lights, but it just makes me not like the tank.

I have 5 blue plus and 3 coral plus.

I just traded a blue plus for an aqua blue special and I don’t like it at all.

Your tank is beautiful as is. But Its something about the "halide white" that we're talking about.. led and even t5 is just different, even then I like a fuller spectrum, but it just doesn't grab you by the eyeballs and rub your brain the same. I'm not qualified to quantify what I'm seeing, but we all see it

 

[oreo54]

I believe it takes all the colors, regardless of source, to achieve 6500k(right? )

Technically.. no but "good" 6500k has all the colors.
Bad-ish color. Many of the whites in these fixtures are 70-ish cri but with different
"misses"... It's an average of the color fidelity of 8 color swatches

Even more extreme (but it is 5500k-ish). See the spectrum. CRI of 13... Really bad color.

 

[Reefering1]

Technically.. no but "good" 6500k has all the colors.
Bad-ish color

Even more extreme (but it is 5500k-ish). See the spectrum. CRI of 13... Really bad color.

Thank you for some technical insight... so..., sorry if silly question, but what is "cri"? And I assume higher is better?

 

[anthony1222]

If it reduces the percentage of blue light put out by the fixture, then the color and PAR output of the light would be impacted.

The color temperature (measured in Kelvin) tells us how warm (red)/cool (blue) a "white" light looks to our eyes.

The spectrum (i.e. the wavelength of light produced) is the actual color of the light(s) produced by the light fixture (for example, a 395nm light emitting diode by itself produces a violet light) - how it looks to our eyes changes depending on all the colors that are produced at one time. For example, if you take a blue light diode (that only produces blue light by itself) and add some yellow, red, and green diodes to it all in one fixture, the light produced by the fixture would appear some variation of white to us (what variation would depend on how much of each light color is in the blend). The more blue added/other colors subtracted, the cooler the light; the more other colors (red, yellow, green, etc.) added/blue subtracted, the warmer the light.

So, the wavelengths and the actual amounts of light put out (measured for coral-keeping purposes as PAR - Photosynthetically Active Radiation) by each light-producing piece of a light fixture (in LED's the light producing pieces are the Light Emitting Diodes themselves) impacts the color temperature of the light as a whole.

All that to say that by decreasing the percentage of blue light the light fixture is putting out, you would change the color temperature (by removing blue light to make the color warmer), and you would reduce the amount of light (PAR) put out by the fixture as well.

I think they're talking about the amount and wavelength of blue light needed to help the corals thrive photosynthetically. Long story short, coral zooxanthellae (and other kinds of algae) use certain kinds of light to produce energy for themselves and their host coral; certain wavelengths of blue light hit a photosynthesis "peak" that helps the zooxanthellae produce the highest amount of energy possible. Without enough blue light from around that peak wavelength, it could be tough for a coral's zooxanthellae to produce enough energy to help the coral thrive.


Also, for the OP, "white" light (6500K and others) can definitely grow corals if they produce the right wavelengths of light in the right quantities.

Blue light has been shown with deeper water corals to help them calcify (i.e. grow) faster in aquariums, but shallower water corals (like many of the ones we keep) can grow faster under white (i.e. full-spectrum) light. Which kind of light is better for a specific coral depends on a number of different factors (wild or captive, the type and amount of light it's used to, how long it has to adjust to different lighting, etc.), but both blue light and white light work fine.

White (full-spectrum) light (with some red light mixed in) is better for photosynthesis, as various photosynthetic pigments have "peaks" in various different light wavelengths (blue, green, red, etc.). The main peaks for both coral zooxanthellae, other types of algae, and plants are typically in the blue and red light wavelengths. Despite zooxanthellae having a peak in the red light wavelengths, however, corals don't like getting too much red light (in at least some cases, they actually actively avoid red light as larvae when they go to settle, and too much red light can kill otherwise healthy corals in aquariums over a long enough time).

These two paragraphs above get at two of the three main reasons why people run just blue lights: 1 - they believe it will help their coral grow faster (it might, dependent on the circumstances of the individual coral), 2 - (like Troylee mentioned above) they believe it will prevent algae growth/give coral an edge over algae in the tank (this is dubious, but it's possible there might be a very small impact of this nature), and 3 - they want their corals to fluoresce more (this one is definitely accurate; fluorescent colors will "pop" more to our eyes under heavy blue/violet light - think glowsticks under blacklight for comparison).

So, if you don't like the look of the heavy blue light, by all means, run white light - your tank will be just fine. Just be aware that changes to your lighting can impact your coral (and fish) color, health, and growth: if the corals are adapted long-term to heavy blue lighting (which may be the case if they've been in a blue-light tank for a while or if they're from deep waters), they will eventually adapt to the new lighting, but you might see some slowed growth, dulled color, and less polyp extension during the adjustment period. If you want to ease them into the transition, then running just blue light for an hour or so in the morning and/or evening as suggested above may help, but I honestly doubt it would be necessary.

(If this block of text didn't scare you off and you want to read more on light and algae/coral, I have links available).

Nice explanation thank you

 

[oreo54]

Thank you for some technical insight... so..., sorry if silly question, but what is "cri"? And I assume higher is better?

Color rendering index. Currently being replaced as inadequate for LEDs.
And this color is judged against a standard.
In this case like D65 or what colors look like under 6500k sunlight

Higher is more accurate. Better is actually a judgement call.

 

[Raul-7]

But don't coral look best under 12-14K?

 

[Troylee]

But don't coral look best under 12-14K?

If you know what you’re doing yes! Fish there’s no comparison!! All fish wash out in blue lighting..

 

[Raul-7]

If you know what you’re doing yes! Fish there’s no comparison!! All fish wash out in blue lighting..

That begs the question; has anyone ran 6500K mixed with 12-14K?

 

[Troylee]

That begs the question; has anyone ran 6500K mixed with 12-14K?

I’m sure plenty of people have over the years between metal halides and different combos of vho bulbs or t5’s… 6500 looks yellow but it’s full spectrum, corals will adapt and grow under any white to blue lighting granted it’s powerful enough.

 

[oreo54]

But don't coral look best under 12-14K?

( Note, I was going to delete the below "discussion" but.....)

I'm not actually going to touch that question but I will comment on the use of the k temp thing.
1) Most if not all lights used for corals are rated by CCT which is a fancy way of saying that are not black body emitters but are " special" i.e have a discontinuous spectrum . You can look it up. Correlated color temperature.
2) IF (and a BIG if) a group of different lights are actually say 14000 CCT it does not mean they look alike nor do they reflect back the same colors. Can be a violet 14000k or a blue 14000k or a green 14000k ect ect.
3) Most lights and especially mh's " k temp" isn't close to what they actually are.
Not only that but it can change depending on ballast
There are exceptions and many at 12000k or less are pretty accurate.
Apparently the " logic" is that they are supposed to " look like" a say 14000k bulb regardless of what they actually are.
This premise gets a bit iffy.
4) There isn't a single current "20000k" bulb that is actually 20000k.
A "14000k" Phoenix is/was actually a "20000k" bulb if you want to use this messy system.
Ushio "14000k" were found to be accurate.
And this is what 14000k looks like:

Point is x coral may look " better" under y bulb but it has little to do with k temp.

The 6500k Iwasaki emitted more blue photons than any of the blue mh's and had more par output than most other bulbs as well ( 2 sort of go hand in hand).
There is no wonder it produced " sunscreens" (though masked by the broad spectrum) and growth than most other mh bulbs.
And that is regardless of the UV and IR that may or may not have been influential in some degree or another.

True 12-14000k aren't that different from true 6500k bulbs
All 3 are pretty " full spectrum".
Generally only a bit bluer looking.

 

[Doctorgori]

pre-Radium I ran everything from 4800k to 6500k,
…ugly & brown corals but they did grow

 

[MartyK]

That begs the question; has anyone ran 6500K mixed with 12-14K?

Iwaki 6500K with a pair of VHO Super Actinics used to be my favorite, and the reason I'm in this thread. Wish I could find equivalents with LED's!

 

[Dburr1014]

I HATE blue lights for reef tanks so I want to keep my reef at 6500k lighting because it mimics the color of daylight and is more true to actual coral reefs but I don't know if it'll hurt the coral. Most pro reefers use bluer light for some reason so that's why Im asking this question.

I'm planning on keeping mostly LPS like euphyllias and SPS like birds nests. I have a radion g6 pro.

I don't think most pros use blues more.

 

[mfinn]

pre-Radium I ran everything from 4800k to 6500k,
…ugly & brown corals but they did grow

At one time back in the middle to late 80's the only bulb I could find were the 65k mh bulbs. ( and vho)
Then one day I saw a ad in a FAMA about a new 10k bulb. It really changed things up for me.

 

[Max93]

With halides,

I have used:

5500k
10k
20k

5500k grew coral super fast, but I didn’t like the yellow look. Then I tried 20k, but the corals grew slow.

So I went for 10k now I’m happy

 

[twentyleagues]

I'm in love with the look of my pheonix14k halides. So white and bright, colors pop, nothing in tank is hidden by color of light; sometimes I just stare at it- can be hard to look away

When I ran mh these were by far the best looking. So crisp and clean. Grew corals great to.

 

[Barncat]

I also hate the blue light; total noob myself so I just stuck with the default settings on the FluvalSmart app (I run a Fluval Nano Marine.) Everything looks good and I have a second new polyp growing on the one coral I have introduced so I guess it's working okay. The lights go actinic blue for couple of hours before bed and an hour in the morning so I get to see my coral and my little bubbletip nem flouresce then.

Harm-wise, it could depend on where your coral is from - deeper corals would probably really only ever encounter blue light due to the way that light filters through water so whiter light may not be as beneficial for them but I think that most of our corals in the hobby is from shallower reefs. (Just my 2 cents as a weird little biology nerd.)

My 30 gallon tank with my Fluval light (ignore the placeholder lids from my old 13.5 gallon tank, had to replace the aquarium in a hurry and I haven't built the new one yet.)