PAR zoas are getting, enough or not?

[Saltwater gardens]

I'am running a Radion XR30w pro over my frag tank plus some natural sunlight. And I have this zoas that are no getting full polyp extension with this amount of PAR. The schedule of the Radion is two hours of 6,500 K, followed by six hours of 12,000 K, and another two hours of 6,500 k before the lights go out. Whats your opinion on why they are no getting complete polyp extension?

PAR they are getting.

Zoas not getting full polyp extension.

 

[jedimasterben]

You sure it is the amount of light they're getting? If that's what you think, you can move them closer to the center of where the light is, which should increase by quite a bit depending on how off center they are.

 

[Saltwater gardens]

I'am not 100% sure if its the amount of light they are getting, but again, the frag is in the edge of the tank 30 cm away form the center. Have you kept zoas at this PAR values, or do you think its too low?

 

[jedimasterben]

My tank doesn't have a lot of variation when it comes to PAR, just high, higher, and WHOA lol. It depends on the species, strain, and where they were collected. Some zoanthids do best in 50-150 PAR, some like 300+. Some strains of Z. sociatus from the Caribbean I've seen growing just a couple of inches of water, PAR over 2000. They do, however, all like strong, intermittent flow.

 

[nivram]

It looks like you may have hydroids on the frag. If so, it may be possible they are irritating the polyps. I would also try different placement as suggested too.

 

[Saltwater gardens]

I'd them with the same light for more than year and half, but the PAR meter I got it recently (two months ago). So when I did my tank upgrade on 13/january/2014 the growth was stopped and the polyp extension was less and less. And I cant get back that perfect place where they were thriving. Also, in my new tank theres a lot more current than in the old one but the water column is lower.

 

[Saltwater gardens]

It looks like you may have hydroids on the frag. If so, it may be possible they are irritating the polyps. I would also try different placement as suggested too.

I'd just removed those hydroids. But in the crate where the frags are placed its full of them, do they have natural predators?

 

[RKLion]

Not a light issue. They would stretch if too little but still be open and even. Probably pests of some sort. Try a dip.

 

[Saltwater gardens]

I'd never done a dip to any coral. Wich product should I get to performed it? And what are the basic tips for dipping corals?

 

[Akwarius]

Try reducing the amount of time they're exposed to 6500k. A ratio of 2-4 hrs of 6500-14k, followed by another 6 hours of 20k or higher always worked well for me.

 

[jedimasterben]

Try reducing the amount of time they're exposed to 6500k. A ratio of 2-4 hrs of 6500-14k, followed by another 6 hours of 20k or higher always worked well for me.

Do you know what that even means?

 

[Akwarius]

Do you know what that even means?

Er...It means I've had first hand experience losing colonies of zoas to over-lighting, particularly with too much low kelvin leds. I respect the fact that some Caribbean and Hawaiian zoas are found shallow, but in a captive system low kelvin, high par doesn't work long term. At least, not for the zoas that people consider 'pretty'.

 

[jedimasterben]

Er...It means I've had first hand experience losing colonies of zoas to over-lighting, particularly with too much low kelvin leds. I respect the fact that some Caribbean and Hawaiian zoas are found shallow, but in a captive system low kelvin, high par doesn't work long term. At least, not for the zoas that people consider 'pretty'.

But you do at least understand that for anything above ~7-8,000K is basically impossible to measure and made up, right? In addition, it is based on how we see it and has nothing to do with the spectral output. You can just as easily make a '14K' light with a metal halide and three LEDs, 470nm, 530nm, and 630nm and your eyes would not be able to see a difference between the two. Color rendition would be horrific on the RGB side, but that's not the point I'm making

So, to sum it up, you're saying that coral farms can't use 6500k lighting to grow zoanthids.

 

[Akwarius]

But you do at least understand that for anything above ~7-8,000K is basically impossible to measure and made up, right? In addition, it is based on how we see it and has nothing to do with the spectral output. You can just as easily make a '14K' light with a metal halide and three LEDs, 470nm, 530nm, and 630nm and your eyes would not be able to see a difference between the two. Color rendition would be horrific on the RGB side, but that's not the point I'm making

So, to sum it up, you're saying that coral farms can't use 6500k lighting to grow zoanthids.

I AM a coral farm, and I do not use 6500k lighting.

I also never gave par recommendations. I simply gave a basic suggestion to the OP, who wants healthier zoas. The OP's question was stated in general Kelvin readings, so that was the terminology I used.

Your points about Kelvin are valid and I've read everything there is on the subject. Perhaps you could provide some reference material for all of us to enjoy.

 

[jedimasterben]

I AM a coral farm, and I do not use 6500k lighting.

I also never gave par recommendations. I simply gave a basic suggestion to the OP, who wants healthier zoas. The OP's question was stated in general Kelvin readings, so that was the terminology I used.

Your points about Kelvin are valid and I've read everything there is on the subject. Perhaps you could provide some reference material for all of us to enjoy.

What I'm saying is that Kelvin temperature is like 'Who's Line is it Anyway?', everything's made up and the numbers don't matter

I've worked on designing lighting for a couple dozen coral farms at this point, the majority of which were lit with Iwasaki 6500k halides, with Radiums being the other choice, except for one that used Chinese 10K bulbs because they could get them for like $20 lol.

I'll try and get someone else in here to give the technical explanation why those measurements are difficult, but I can at least say that there is no standard used since you can take a dozen '14k' lights and put them next to each other, strike them all properly (the right ballast, the right starter, etc), and they'll all look different.

 

[Saltwater gardens]

Try reducing the amount of time they're exposed to 6500k. A ratio of 2-4 hrs of 6500-14k, followed by another 6 hours of 20k or higher always worked well for me.

I'am curious to know why they should be exposed to higher kelvin rates where the wavelenght is shorter in term of spectral color, than a 12-14,000 k where thet can use "more wavelenghts". I'am still trying to really understand all this concept of kelvin, and the amount of PAR they should recieved. If you have any article or link where it explains it, please share it. And thanks for the post.

 

[Akwarius]

I'am curious to know why they should be exposed to higher kelvin rates where the wavelenght is shorter in term of spectral color, than a 12-14,000 k where thet can use "more wavelenghts". I'am still trying to really understand all this concept of kelvin, and the amount of PAR they should recieved. If you have any article or link where it explains it, please share it. And thanks for the post.

Look at this graph:

Shorter wavelengths are higher energy.

Now look at this graph:

See that longer wavelengths are absorbed more quickly. Now factor in the angle of sun on the horizon, penetrating the most light in the middle of the day, and you should conclude that running 6500k for more that a few hours is unnecessary. At best, it will only cause additional algae, and at worst, it will brown corals.

Another useful graph:

You'll see that longer wavelengths are utilized by coral far less than shorter wavelengths.

Just to be clear, I do not advocate running only blue leds or blue plus t5s. I've tried this and the zoas always degrade over time. The key is finding the right balance, such as can be found in a Radium bulb or the right Radion pro settings.

Again, please excuse the oversimplifications. This issue is very complex and zooxanthellae research is ongoing.

 

[jedimasterben]

Look at this graph:

Shorter wavelengths are higher energy.

Photons of a shorter wavelength do, indeed, have higher energy (measured in electron volts, or eV). A 660nm red photon has an energy of about 1.88eV, a 450nm blue photon has an energy of 2.76eV, but this does not matter to photosynthesis, where a single photon, regardless of the energy, gives the photosynthetic process the same energy (hence 'a photon is a photon is a photon).

Now look at this graph:

See that longer wavelengths are absorbed more quickly. Now factor in the angle of sun on the horizon, penetrating the most light in the middle of the day, and you should conclude that running 6500k for more that a few hours is unnecessary. At best, it will only cause additional algae, and at worst, it will brown corals.

This one is just plain misleading. This is more what it should look like relative to the corals collected for our hobby.

Here is light penetration relative to the angle of incidence.

And measurements over the course of a day, per Dana Riddle.

Curious how a 6500K light source (btw, the Radion is not capable of such a low color temperature, the cool white LEDs used in it are above 6500K) will cause algae.

Another useful graph:

You'll see that longer wavelengths are utilized by coral far less than shorter wavelengths.

PCP (peridinin-chlorophyll protein complex) actually extends pretty far into green - its FWHM extends from ~410-540nm.

This doesn't necessarily mean that a 540nm photon is any less effective than a 450nm photon, it just determines how many of those presented the coral is capable of collecting.

 

[Akwarius]

Well Jedi, it looks like you have a debate partner for the day. Hopefully the OP and readers can glean some useful information from this. Also keep in mind that my entire livelihood depends on the correct lighting of zoas, so take or leave what I have to say.

"This doesn't necessarily mean that a 540nm photon is any less effective than a 450nm photon, it just determines how many of those presented the coral is capable of collecting."

How about this study: Red light negatively affects health of stony coral ? Advanced Aquarist | Aquarist Magazine and Blog

"In layman's terms, the study reinforces the theory that corals use red light as their gauge for light intensity and regulates photosynthesis according to the amount of detected red light."

6500k emits too much of the red spectrum, causing photoinhibition.

Next point:

"Curious how a 6500K light source (btw, the Radion is not capable of such a low color temperature, the cool white LEDs used in it are above 6500K) will cause algae."

The Radion pro has red, green, and white leds. With the blues turned off, one can achieve color temperatures at or lower than 6500k. See for yourself, grow chaeto under blue leds vs white leds and see which grows faster.

Last point:

Reflectance and angle of penetration are two separate things. The lower the sun is on the horizon, the farther the photons will need to travel through water to reach the coral. Not only does PPFD decrease at dusk and dawn, but color temperature as well.

 

[Saltwater gardens]

, jfhfhI decided t
I decided to reschedule my lamp according to the points made in this debate. From tomorrow my tank will a new schedule, instead of four hours of 6,500 K now its going to be four hours of 20,000 K, and 6 hours of 14,000 K. Anyway here I leave pciture of my schedule I would like to know your opinions. Also tomorrow I will upload a picture of how the zoas and corals are, and tow months after another to see results.

Any suggestion I would like to know. Possibly because it is a problem of spectral color should I increase the intensity of my lamp to get higher PAR, or 94 it is ok?