What is better for SPS growth & Color? Short or long photoperiod?
- Thread starter fishfanatic06
- Start date
fishfanatic06
New member
So here's another question. Say your are running a tank with a higher intensity bulb (10k) and one tank with a lower intensity bulb (20k) of the same wattage. Since the 10k has the higher intensity you would run your lighting for a shorter time period to reach the saturation point. Now, the tank with the 20k bulb would have less intensity than the 10k bulb, but you could still reach the saturation point in your corals with the 20k bulb by running it for a longer photoperiod. So why does everyone say you will get better growth with a lower temperature bulb, if you can reach saturation point with both the 10k and 20k bulb?
JMO!
Correct me if I am wrong.
Thanks!
JMO!
Correct me if I am wrong.
Thanks!
So corals will just basically sit there after they reach saturation point? Does that mean we can divide the photoperiod? Let's say they reach saturation point after 6hrs, can I turn off the light and let them rest for say, another 6hrs, then turn the light back on? Will that promote growth?
fijiblue
Active member
fishfanatic06 - If only it was that easy!
There are more differences between 10k and 20k besides visual color. According to Tyree's Stony Reef Builders book, corals can grow from light even if it is not the most efficient as long as it is abundant. Blue light penetrates the water the farthest. Even though a 10k might produce higher PAR numbers, the blue light is more easily absorbed by the algae within the coral. Red light reproduces cells within the coral much faster hence the growth. Bluer light causes the cells to thicken and grow larger hence the coloration. Same applies to plants as well.
mastawong - Interesting thought that would require experimentation, although im sure there would be at least one negative result from doing so. You must keep in mind that a coral calcifies at night making the dark part of a photo period equally important as the light part.
There are more differences between 10k and 20k besides visual color. According to Tyree's Stony Reef Builders book, corals can grow from light even if it is not the most efficient as long as it is abundant. Blue light penetrates the water the farthest. Even though a 10k might produce higher PAR numbers, the blue light is more easily absorbed by the algae within the coral. Red light reproduces cells within the coral much faster hence the growth. Bluer light causes the cells to thicken and grow larger hence the coloration. Same applies to plants as well.mastawong - Interesting thought that would require experimentation, although im sure there would be at least one negative result from doing so. You must keep in mind that a coral calcifies at night making the dark part of a photo period equally important as the light part.
kev apsley
In Memoriam
<a href=showthread.php?s=&postid=12406493#post12406493 target=_blank>Originally posted</a> by fijiblue
Roger-
Sorry for the confusion. Let me give you an analogy. Think of a coral as a cup. Let's say the cup is 16 ounces and you want to fill it up with water. There are two ways you can do this. You can either dump all the water in at once or drip it slow over the course of the day. Either way, the cup is 16 ounces so dumping extra water quickly and trying to overfill the cup will just result in wasted water spilling out. A coral is the same way. You can give it a high amount of intensity or a low amount. Either way the coral only needs X amount to live. If you give it a higher amount (meaning more than is needed to sustain), the coral is going to be full in less time and then reject the rest of the light because it has reached it's saturation and ultimatley result in photoinhibition. If you use a lesser intensity, the coral will be able to use the energy at a constant rate throughout the day until it is full in the end. The goal is finding the middle ground.
I hope that wasn't too confusing because I think I just confused myself!
That was a great analogy! I was trying to follow along but I am just a simple man
rogergolf66
im an addict lol
great thread!!!
Roger
Roger
green_frogspawn
New member
corals use the calcium in the water to grow, thus calcifying
MCsaxmaster
New member
Hi guys,
Analogies are great, and I love them, but sometimes important information gets lost through an analogy. Let me just clear up a couple of points.
Kinda sorta. The amount of time for photosynthesis to reach saturation under sufficient light intensity is much less than 1 second. Hit a coral, alga, plant, or whatever with a strong burst of light for 1 second (or 0.8 s, as with a PAM fluorometer) and the photochemistry will be completely saturated.
Corals may take hours to reach saturation in nature for one reason and one reason only: sunlight is dim in the early morning, and thus the intensity is below a saturating intensity. If the sun just suddenly appeared in the sky, was out for 12 hrs and then was gone (similar to how aquarium lights work) we would see no photosynthesis, then a constant rate for 12 hrs (assuming no clouds) and then no photosynthesis again. Light intensity determines where on a P/I curve we fall. Photoperiod is effectively irrelevant (though it takes minutes to significantly affect the xanthophyll cycle, which is an important non-photochemical quencher at high light levels).
Photoinhibition can be related to photoperiod since it is related to physiological damage of the photosystems, not simply to the biochemistry of photochemistry. Light that is too bright for 8 hrs is worse than light that is too bright for 1 hr. After photodamage has been done it takes time to repair it, and after significant photodamage it can take days to repair everything.
If we hit a coral (or whatever photosynthetic critter) with strong light for a short period of time, much of the light cannot be used for photosynthesis. The biochemical processes can only go so fast. With sufficient light (= saturation) the photochemistry is what determines the rate of photosynthesis, not the light intensity. Thus, any increase in light beyond that point will simply increase the amount of energy lost to chl a fluorescence or through the xanthophyll cycle. However, as the xanthophyll cycle becomes exhausted, there is more photodamage and more photoinhibition, as mentioned. Thus, if we give a short period of very strong light and a long period of moderate light (= saturating) wherein we provide equivalent total quantities of light (PAR x photoperiod) we will get less photosynthesis with the short, intense light. Much of the light cannot be used because photosynthesis is going at a max. If rates of photosynthesis were similar during each period (before we get into significant photoinhibition) the corals would have less photosynthate at the end of the day with the shorter photoperiod simply because it is shorter. A short, bright photoperiod is effectively equivalent to a short, moderately bright photoperiod, except that we waste a lot of electricity with super-bright lighting. For some corals, we can easily get light that is stronger than needed. For some others we need the sort of intensity we would consider “very bright†just to reach saturation.
The ideal, without any question, is an appropriately long photoperiod with light that is bright enough to put our corals right about at the saturation point. In this way we aren’t wasting electricity providing useless light (or harming the corals by providing too much), but we are encouraging rapid growth and calcification.
Chris
Analogies are great, and I love them, but sometimes important information gets lost through an analogy. Let me just clear up a couple of points.
<a href=showthread.php?s=&postid=12406493#post12406493 target=_blank>Originally posted</a> by fijiblue
Roger-
Sorry for the confusion. Let me give you an analogy. Think of a coral as a cup. Let's say the cup is 16 ounces and you want to fill it up with water. There are two ways you can do this. You can either dump all the water in at once or drip it slow over the course of the day. Either way, the cup is 16 ounces so dumping extra water quickly and trying to overfill the cup will just result in wasted water spilling out. A coral is the same way. You can give it a high amount of intensity or a low amount. Either way the coral only needs X amount to live. If you give it a higher amount (meaning more than is needed to sustain), the coral is going to be full in less time and then reject the rest of the light because it has reached it's saturation and ultimatley result in photoinhibition. If you use a lesser intensity, the coral will be able to use the energy at a constant rate throughout the day until it is full in the end. The goal is finding the middle ground.
I hope that wasn't too confusing because I think I just confused myself!
Kinda sorta. The amount of time for photosynthesis to reach saturation under sufficient light intensity is much less than 1 second. Hit a coral, alga, plant, or whatever with a strong burst of light for 1 second (or 0.8 s, as with a PAM fluorometer) and the photochemistry will be completely saturated.
Corals may take hours to reach saturation in nature for one reason and one reason only: sunlight is dim in the early morning, and thus the intensity is below a saturating intensity. If the sun just suddenly appeared in the sky, was out for 12 hrs and then was gone (similar to how aquarium lights work) we would see no photosynthesis, then a constant rate for 12 hrs (assuming no clouds) and then no photosynthesis again. Light intensity determines where on a P/I curve we fall. Photoperiod is effectively irrelevant (though it takes minutes to significantly affect the xanthophyll cycle, which is an important non-photochemical quencher at high light levels).
Photoinhibition can be related to photoperiod since it is related to physiological damage of the photosystems, not simply to the biochemistry of photochemistry. Light that is too bright for 8 hrs is worse than light that is too bright for 1 hr. After photodamage has been done it takes time to repair it, and after significant photodamage it can take days to repair everything.
If we hit a coral (or whatever photosynthetic critter) with strong light for a short period of time, much of the light cannot be used for photosynthesis. The biochemical processes can only go so fast. With sufficient light (= saturation) the photochemistry is what determines the rate of photosynthesis, not the light intensity. Thus, any increase in light beyond that point will simply increase the amount of energy lost to chl a fluorescence or through the xanthophyll cycle. However, as the xanthophyll cycle becomes exhausted, there is more photodamage and more photoinhibition, as mentioned. Thus, if we give a short period of very strong light and a long period of moderate light (= saturating) wherein we provide equivalent total quantities of light (PAR x photoperiod) we will get less photosynthesis with the short, intense light. Much of the light cannot be used because photosynthesis is going at a max. If rates of photosynthesis were similar during each period (before we get into significant photoinhibition) the corals would have less photosynthate at the end of the day with the shorter photoperiod simply because it is shorter. A short, bright photoperiod is effectively equivalent to a short, moderately bright photoperiod, except that we waste a lot of electricity with super-bright lighting. For some corals, we can easily get light that is stronger than needed. For some others we need the sort of intensity we would consider “very bright†just to reach saturation.
The ideal, without any question, is an appropriately long photoperiod with light that is bright enough to put our corals right about at the saturation point. In this way we aren’t wasting electricity providing useless light (or harming the corals by providing too much), but we are encouraging rapid growth and calcification.
Chris
MCsaxmaster
New member
Huh-uh. Photosaturation has nothing to do with photoperiod (on timescales longer than a few tenths of a second). Intensity is the important piece while photoperiod is meaningless. In this case the brighter bulb will bring most corals close to the photosaturation (assuming the bulb and corals aren’t too far apart) whereas the dimmer bulb won’t get them nearly as close. Thus, the corals would be light-limited under the 20K bulb, but much less so under the 10K bulb. With a higher rate of photosynthesis the corals have a higher energy budget and tend to have faster growth.
Again, light intensity is the important piece, not photoperiod. If a light source is not sufficiently bright to allow a coral to reach photosaturation, you can leave it on until the end of time and photosynthesis will never be saturated with light. Even though the instantaneous rate of photosynthesis would be higher under the brighter bulb in most cases (depends on the exact intensity and the characteristics of the corals, i.e., P/I curve), if the photoperiod were sufficiently long with the dimmer bulb the net production of photosynthesis might be similar. Considering how dim most 20K bulbs are, however, you’d be looking at photoperiods approaching 24 hrs to make up the difference
Of course, nobody does that. Most folks that run those dimmer bulbs still use similar photoperiods. Photosynthesis proceeds more slowly under these bulbs and thus, at the end of the day, the coral has less photosynthate at its disposal, a smaller energy budget, and tends to grow more slowly.
Chris
miwoodar
Likey the bikey
Chris,
My 20K's have exceeded my expectations with regards to growth rates. Indeed, if I were getting such growth with 10K bulbs, I would be here on RC telling everyone to get high PAR 10K bulbs or their growth would suffer. So my question is thus - how far away from photoinhibition are we talking about with, say, a 20K 250 watt Radium at a distance of, say, 6" above water and another 6" below water. 10 hours on, 14 off. I know that this is an impossible question --- maybe just an example or two if you have any.
Here are Joshi graphs for my 20K's: http://i113.photobucket.com/albums/n231/miwoodar/MHComparison.jpg
I wish the articles linked before used larger an more applicable (to aquarists) study groups!
My 20K's have exceeded my expectations with regards to growth rates. Indeed, if I were getting such growth with 10K bulbs, I would be here on RC telling everyone to get high PAR 10K bulbs or their growth would suffer. So my question is thus - how far away from photoinhibition are we talking about with, say, a 20K 250 watt Radium at a distance of, say, 6" above water and another 6" below water. 10 hours on, 14 off. I know that this is an impossible question --- maybe just an example or two if you have any.
Here are Joshi graphs for my 20K's: http://i113.photobucket.com/albums/n231/miwoodar/MHComparison.jpg
I wish the articles linked before used larger an more applicable (to aquarists) study groups!
Last edited:
MCsaxmaster
New member
<a href=showthread.php?s=&postid=12419050#post12419050 target=_blank>Originally posted</a> by fijiblue
fishfanatic06 - If only it was that easy!
Iwasaki 6500 K bulbs and most 10 K bulbs produce more blue light than 12, 13, 14, 15, 20, 50K etc. bulbs. The major difference is that the “blue†bulbs produce a lot of light at ~450 nm and little of anything else, making them look blue, while the Iwasakis and 10 K bulbs have a more balanced spectrum. They may produce more blue light, but since they also produce green and red and everything in between the light appears whitish to our eyes, instead of bluish.
QUOTE]<a href=showthread.php?s=&postid=12419050#post12419050 target=_blank>Originally posted</a> by fijiblue
Red light reproduces cells within the coral much faster hence the growth. Bluer light causes the cells to thicken and grow larger hence the coloration. Same applies to plants as well.[/QUOTE]
Hmmmm, I’m not so sure about the effects of light spectrum on zoox. growth. I’d like to see those references
Either way, however, the only color zoox. can contribute to corals is some shade of golden brown or brown. Any color besides brown comes from pigments the corals produce.
QUOTE]<a href=showthread.php?s=&postid=12419050#post12419050 target=_blank>Originally posted</a> by fijiblue
mastawong - Interesting thought that would require experimentation, although im sure there would be at least one negative result from doing so. You must keep in mind that a coral calcifies at night making the dark part of a photo period equally important as the light part. [/QUOTE]
I’m not sure where the idea came from that corals only calcify at night (I’ve heard it many times on RC and elsewhere), but it is simply incorrect. The MAJORITY of coral calcification is done during the day. Typically the rate of light calcification (photosynthesis saturated) is on the order of 3x as fast as the rate of dark calcification. For a typical coral, on the order of 75% of the daily calcification is done during the light period whereas 25% is done during the dark period.
MCsaxmaster
New member
Oye vey. Unfortunately, I really can't answer the question, but we can do a thought experiment that should prove useful.
The PPFD for that bulb in those conditions (no reflector, 18" from the detector) is in the neighborhood of ~65-70 umol photons/m2/s. As a note, PPFD = photosynthetic photon flux density and PAR = phosynthetically active radiation. They are two terms for the same measure.
Assuming the bulb is a point source, which isn't a bad assumption without a reflector, at 12" from the bulb in air we can calculate the light intensity using the inverse square rule. 18" is 1.5x as far from the bulb as 12" and the light intensity drops as the square of distance: 1.5^2 = 2.25. Thus, at 12" we calculate a light intensity 2.25x as bright as at 18", or 146-158 umol photons/m2/s.
Presumably you're using a reflector, and that will increase the light intensity at any given distance. It also messes up the geometry of the light source such that the inverse square rule is no longer a good model. For the sake of argument, let's just assume that the reflector increases light intensity by 25% on the low end and 100% on the high. The true value is probably somewhere in between.
Thus, we'd have a light intensity at 12" of 183-198 umol photons/m2/s on the low end to 292-316 umol/m2/s on the high end. The true value is probably somewhere in between.
The amount of light necessary to saturate the zoox. in hospite (keep in mind, it's the zoox. that are doing the photosynthesis, not the corals) varies dramatically among different strains/species and also within the same strain/species due to differences in previous conditioning.
Corals that are adapted to lower light conditions (not including those that are adapted to ultra-dim conditions, like some Leptoseris) often saturate with light intensities in the neighborhood of 80-120 umol photons/m2/s. They may start to experience photoinhibition with light intensities in the neighborhood of 300-400+ umol photons/m2/s. If we compare these very general ranges, and I really, really want to stress that this is very general, we can see that your light source would likely photosaturate these corals, but likely is not strong enough to induce photoinhibition. For corals adapted to lower lighting, which includes a lot of corals (don't believe the rubbish about "sps" need this and "lps" need that--such distinctions are utterly useless here), this is probably a very appropriate light intensity.
Now, some corals are more abundant in shallower water. They host zoox. that do better in more light and those zoox. are often physiologically adapted for higher light. For a lot of the corals that grow best at mid-depth to shallower depths we are looking at ~250-350 umol photons/m2/s needed to saturate photosynthesis. We don't usually see significant photoinhibition until 600-800+ umol photons/m2/s in these corals. The majority of corals fall in this category.
If we look to your light source, we can see that we would have light intensity anywhere between well under saturation to right around saturation, depending on the assumptions we make in calculating the light intensity. Realistically, the only way to have an idea of where you stand is to measure the light intensity. At this distance with these bulbs, you aren't going to photoinhibit these corals.
Some corals host zoox. tolerant of extremely bright light and preferentially grow in very shallow environments. The best example of this I can think of is Acropora palmata (Caribbean Elkhorn coral). This usually grows in the top 3-5 m of water, and almost never any deeper. There are many Pacific corals that grow in the same sort of environment, though most of them can also be found elsewhere. Corals like these may not exhibit photosaturation until ~400-500 umol photons/m2/s. Some of these may experience photoinhibition in light intensity as low as 700-800 umol photons/m2/s, but most can tolerate light levels well in excess of 1000 umol photons/m2/s before significant photoinhibition.
These corals would not be photosaturated by your lights, and wouldn't come even close to photoinhibition.
Realistically, in order to talk specifics we'd need to know the light intensity you're actually dealing with and a lot more about the corals in question.
I will say that I strongly agree with Dana Riddle's general premise that people have often gone overboard with lighting, and are likely harming some corals as a result. However, I think that really needs to be tempered (which is latest article does somewhat) with the variation that exists among corals. Some corals really are going to do a lot better with moderate lighting (T5s and low-wattage halides). Others, however, are going to dig really bright light from high intensity halides. This has everything to do with the type of zoox. the corals host (or are hosting, since some corals can host many types of zoox.) as well as previous conditioning.
Just to repeat, designations like "sps" and "lps" are so useless as to border on dangerous if applied in situations like this. There are "sps" corals that will fry under intense light and there are "lps" corals that will do best under very bright light. Polyp size is just utterly useless when it comes to describing husbandry needs like this. Rant over
Hope this helps
Chris
MCsaxmaster
New member
Ha, well, a time or two...or dozens
Heres my experience. I run 2 175w 20ks for 6 hours. 2 HO T5 blue+ for 12hours. on a 65 gallon.
I ran 10k halides for 10 hours, till recently.
Since Ive lowered the hours and started bi-weekly night time feedings plus AA's the corals have better color and are growing fast.
less light means less sugar. thats what the corals get from the zooxanthalle, sugar.
Stop the junk food :rollface: :rollface:
More feedings, mean more protein. They have those stinging tentacles for a reason
This was the answer in my tank. I thought about going to 250w but tried this first. I couldnt be happier.
I ran 10k halides for 10 hours, till recently.
Since Ive lowered the hours and started bi-weekly night time feedings plus AA's the corals have better color and are growing fast.
less light means less sugar. thats what the corals get from the zooxanthalle, sugar.
Stop the junk food :rollface: :rollface:
More feedings, mean more protein. They have those stinging tentacles for a reason
This was the answer in my tank. I thought about going to 250w but tried this first. I couldnt be happier.
Last edited:
MCsaxmaster
New member
Google "light enhanced calcification"--you'll get lots of hits.
