What is better for SPS growth & Color? Short or long photoperiod?

[fishfanatic06]

So what's better? Short or long photoperiod? I am thinking of only running a 6 hour photoperiod. I am currently running a 10 hour photoperiod with 2x150 watt hamilton 14k halides on a 55 gallon tank. I know a lot of people who had color and growth improvement after running their main/halide lights for a shorter period (4-7 hours).
Thanks!

 

[stevedola]

you could turn 1 on at a time and stagger them on/off.

ie
9am actinics on
10am 1 mh on
12pm 2nd mh on
4 pm 1mh off
6pm 2nd mh off
7pm actinics off

i know people that swear by that method. however they have 4-6 mhs over larger tanks so its different. they call it the "high noon" method. i think their nutz but what ever works. makes some sense I guess and decreases elec bill.

 

[MCsaxmaster]

A longer photoperiod should increase the rate of calcification at the least, and usually this translates into more linear extension (= growth). Photoperiod likely has little to do with coloration under normal circumstances. Instead, light intensity is far more important.

 

[fijiblue]

Instead, light intensity is far more important.

Agreed. Doesn't matter how long you run it, but rather if you coral is reaching saturation or not with the intensity that you have.

 

[fishfanatic06]

So, how do you know when your corals reach saturation?

 

[fijiblue]

just ask them. Seriously, I would look for different signs, ie growth, ph, etc. When I decreased my light intensity, I noticed my PH go up from 8.1 to 8.34. I would assume then that the corals were photosynthesizing for the whole part of my light cycle rather than just part of it and then reaching photoinhibition thus using up more of the co2 from my tank. Either that or you could buy a PAM meter to measure the Electron Transport Rate (ETR).

Here is an article by Dana Riddle that has a useful guidline at the bottom to roughly measure you PAR and place corals accordingly.HTH
http://www.advancedaquarist.com/2007/3/aafeature1/view?searchterm=too much light

 

[Genetics]

<a href=showthread.php?s=&postid=12403778#post12403778 target=_blank>Originally posted</a> by MCsaxmaster
A longer photoperiod should increase the rate of calcification at the least, and usually this translates into more linear extension (= growth). Photoperiod likely has little to do with coloration under normal circumstances. Instead, light intensity is far more important.

I'm curious with your statement that "this translates into more linear extension". Are you talking about the photoperiod length resulting in growth or the growth of the coral itself? The later should be logarithmic in growth at saturation since the new growth would provide additional area for more growth.

 

[rogergolf66]

<a href=showthread.php?s=&postid=12404416#post12404416 target=_blank>Originally posted</a> by fijiblue
. When I decreased my light intensity, I noticed my PH go up from 8.1 to 8.34. I would assume then that the corals were photosynthesizing for the whole part of my light cycle rather than just part of it and then reaching photoinhibition thus using up more of the co2 from my tank. (ETR).


HTH
http://www.advancedaquarist.com/2007/3/aafeature1/view?searchterm=too much light

so you are saying if I read this right that with let light you are getting more photosynthesizing? am I reading this backwards?

Roger

 

[MCsaxmaster]

<a href=showthread.php?s=&postid=12404337#post12404337 target=_blank>Originally posted</a> by fishfanatic06
So, how do you know when your corals reach saturation?

You have to take appropriate physiological measurements to make a P/I curve (photosynthesis vs. irradiance). There are three proxies people typically use as a proxy for photosynthesis: 1) O2 production (classic and commonly used), 2) CO2 fixation (usually using 14C, though measuring change in TCO2 works in water), or 3) producing an Relative ETR (electron transport rate) vs. I curve by measuring effective quantum yield of photosystem II with a PAM fluorometer.

Using O2 production or CO2 fixation works well for determining physiological responses to light intensity, as well as for measuring net production. More and better information can be produced by combining O2 production and CO2 fixation within an experiment (this is a lot of work though). Using a PAM fluorometer works well for determining physiological responses, but isn’t so hot for calculating net photosynthesis. Hence, it would work for our interest here, but isn’t a good method for many other applications. PAM fluorometry is also so-so at resolving rates of photosynthesis in large structures like corals or higher plants (i.e., things other than microalgae) at higher light levels. It isn’t the magic bullet a lot of folks seem to think it is, but it is a very useful tool.

Since none of this is at all feasible for anyone outside a lab that has such equipment (a diving PAM starts at about $16,000 ), it is necessary to work off best-guess approximations produced by other folks. You can get an idea of the neighborhood you’ll see saturating light intensity for a given coral adapted to those conditions. As linked above, Dana Riddle has written marvelous articles about the subject. Having said that, PAM fluorometry is, again, no magic bullet, and I think it is important to use another method (e.g., O2 production) before we get too comfortable with the numbers we produce. If I had one criticism of articles like the one linked above, it would be that the datasets are rather small. While I strongly agree with the general sentiments, I would like to see more done before we start talking about saturating and photoinhibiting intensities for any coral species, especially those that live over a range of depths.

Chris

 

[MCsaxmaster]

<a href=showthread.php?s=&postid=12404535#post12404535 target=_blank>Originally posted</a> by Genetics
I'm curious with your statement that "this translates into more linear extension". Are you talking about the photoperiod length resulting in growth or the growth of the coral itself? The later should be logarithmic in growth at saturation since the new growth would provide additional area for more growth.

Calcification is equivalent to the mass of skeletal accretion in corals. While calcification is generally related to linear extension, the two can be decoupled. Corals can slow down linear extension but maintain calcification. This results in increased skeletal density. On the other hand they can increase linear extension and maintain calcification which decreases skeletal density. If both processes change at the same time, we’ll see a bigger change in skeletal density.

Skeletal density does vary naturally on a roughly yearly cycle (high density and low density bands). However, the changes are relatively modest under normal circumstances, and in general we would expect linear extension to correlate with calcification. With a longer photoperiod we should see a longer period of light-enhanced calcification with a 24 hr period, and hence more calcification during that period. Normally we’d expect to see an increase in linear extension, which is what I think most folks would mean when they say “growth” but since the processes of calcification and linear extension can be decoupled, it does not necessarily follow that an increase in calcification MUST result in increased linear extension. It is possible that we could just end up with stronger, better calcified coral skeletons. Having said that, I don’t think it’s particularly likely.

Chris

 

[MCsaxmaster]

<a href=showthread.php?s=&postid=12404929#post12404929 target=_blank>Originally posted</a> by rogergolf66
so you are saying if I read this right that with let light you are getting more photosynthesizing? am I reading this backwards?

Roger

At low light intensity, photosynthesis is low due to light limitation. As light intensity rises the rate of photosynthesis will rise, but eventually level off. With sufficient amounts of light, the photochemistry becomes limiting instead of the amount of light. If we further increase light intensity, the photocenters of PSII continue to gather light, but have to dump it through the xanthophyll cycle because the rest of the photochemistry is already maxed out. If we increase light more, the xanthophyll cycle becomes maxed out and we end up with a whole light of extra absorbed energy. When plants find themselves in this situation, the production of reactive oxygen species (ROS) goes sky high and causes damage to the photosystems. As we damage our photosystems, the rate of photosynthesis begins to drop.

Thus, at low light intensity photosynthesis is light-limited and increasing the amount of light increases photosynthesis. At moderate light intensities photosynthesis is saturated with light and is effectively constant. Excess light energy, if there is any, is dumped through the xanthophyll cycle. At very high light intensities the production of ROS goes up, photosystems are damaged and the rate of photosynthesis goes down due to a limitation of the number of functional reaction centers. That is termed photoinhibition. For many corals adapted to shallow water, photoinhibition is probably not something we have to be too concerned with. However, with corals that are adapted to mid-depth or deep water, or those that live in cryptic locations in shallow water (and this probably includes most corals) photoinhibition is a real concern with very bright lights.

Chris

 

[stony_corals]

<a href=showthread.php?s=&postid=12404929#post12404929 target=_blank>Originally posted</a> by rogergolf66
so you are saying if I read this right that with let light you are getting more photosynthesizing? am I reading this backwards?

Roger

Roger, what I believe he was saying was that he found that by decreasing light intensity, his pH ran higher. He was thinking that this may have been due to his corals reaching the saturation state (when running more intensity) and weren't photosynthesizing. When he reduced the light intensity, he found the pH ran higher and attributed this to more photosythesis due to his coral not reaching saturation.

 

[stony_corals]

Gotta love wikipedia...

http://en.wikipedia.org/wiki/Xanthophyll

Thanks Chris for the explanation...

 

[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!

 

[rogergolf66]

interesting theroy. any reading or links to back this up? Im not saying your wrong but haven't heard it put that way before.

Thanks

Roger

 

[fishfanatic06]

What is a negative consequence from photoinhibition? Slowed Growth? Loss of color? Zooxethellae are lost?
Thanks?
Sorry if these questions sound kinda dumb.

 

[IndyMatt]

fishfan I am right there with you, I have no freaking clue what photoinhibition is or what the consequences of it are.

 

[rogergolf66]

Ok great info thank you

I didn't realize that it could only take so much light in per day. I thought it could only take in so much light in at a time.

Can you exsplain more about how the PH helped you tell if you corals were saturatated or not? how? and how can I check the same thing?

Thank you learning alot in a way that I can understand. most if the articals are writen in a way that is hard to understand when you get into this stuff.

Roger

 

[fijiblue]

Roger- There was no theory stated, but rather an anology to how a corals functions. If you want to get into detail, I would recommend readings from the website I linked earlier.

In my case, I observed the PH readings of my tank for a week before making any changes. After the change, the PH went up which told me the corals were now photosynthesizing for the whole duration of my lighting period instead of before where they would reach saturation and inhibition, ending photosynthesis and ultimately lowering my PH.

fishfanatic06 - There are no dumb questions...the only dumb one is the one you don't ask. I would read up on the article I linked above.

 

[rogergolf66]

no list out there on how much light a coral needs to help on setting up near the top or bottom of tank?

Great read thanks for all the info. I only have about 6months on SPS corals I switched over from softies.

I have about 80 frags/collonies now but reading/learning alot