Refugium Lighting - 24/7 is Bad-Says Kent Marine University

[Henry1]

I ran my refugium with several species of caulerpa 24/7 under dual 65W PC (10K)
With the intent of cutting down heat, I modify the regime to 1 light at night and 2 in the day.

On the third day of this schedule, C. Racemosa and Sertularioides went sexual.

Could a reduction of lighting also trigger this response?

Anyway, I'm going back with dual lights 24/7. :?

 

[danmhippo]

I have lots of macro in my office tank (lit 24/7) and I moved some to stock them in my outdoor pond. Outdoor pond, being on natural lighting schedule, over half of them went sexual and rotted out on the second day.

I will have to wait and see if the remaining pond batch will grow as fast, if not faster, than the refugium macros.

 

[Anonymous]

I ran my refugium with several species of caulerpa 24/7 under dual 65W PC (10K)
With the intent of cutting down heat, I modify the regime to 1 light at night and 2 in the day.

On the third day of this schedule, C. Racemosa and Sertularioides went sexual.

Could a reduction of lighting also trigger this response?

Anyway, I'm going back with dual lights 24/7. :?

i don't think it's the photoperiod, per se, but the change itself that triggered it.

has anyone here had sexual reproduction triggered when doing the reverse?(i.e.-going from on/off to 24/7)

 

[Anonymous]

Dr. Reef, (and others) you're bringing some good information to the table here. I wonder if there are any scientists who have studied algea in Alaska during the summer who could give us some insight into our refugium systems? Could I lay this question on you Dr. Reef? Maybe it would be of interest to your classroom during said experiment?

po

 

[ophiuroid]

i don't think it's the photoperiod, per se, but the change itself that triggered it.

I agree with this. For example, Brittlestars (and a variety of inverts) are often induced to spawn using temperature/lightshock methods. Changes in photoperiods are often cues for reproduction. I don't think that it is a good idea to abruptly go from one extreme to the other. If anything suddenly happens, then it is assumed it was the photoperiod, and not the shock from the sudden change. As you can probably imagine, for a wild organism, a change such as going from 12 hours light to 24 hours light in one day would be a major shock.

I prefer 12/12 simply because it is a more natural photoperiod. There are a lot of animals in our systems that do not like bright light. Heck, I wouldn't see my brittlestars if I kept the lights on all the time.

 

[Anonymous]

I changed form 24/7 to reverse daylight a while back and still haven't notice any significant difference. Except reduced film algea in the refugium and reduce power bill. Nothing has ever gone sexual using either photoperiod.

My refugiums sucks, but that's another story. :roll: I'll start a new post about that after I relocate my tanks to my new house in a couple of week.

Louey

 

[jabrams]

dont go cutting your lights back unless you are having a problem. I have been running my fuge for 2 years on 27/7--im not about to switch, i have not reason too. and i have 7 species of macro algea

 

[monkeyboy]

I run about 11 hours of light over the 'fuges because I use all non-caulerpa macro-algaes. There's several fast growing macroalgae's that can be used in the place of caulerpa without the nasty sideaffect of losing the whole 'fuge to a horny piece of algae.

I don't really see what the fixation is with caulerpa besides its availablity? Try out some dictyota, ochodes (don't have MCRA in front of me, think that's the spelling), or some gracilliara sp. macro's and 'fuge away!

 

[monkeyboy]

I don't know about cracking on the prestiged Kent Marine University's stance on caulerpa or you may not make Dean Jack Kent's list...

 

[dizzy]

dont go cutting your lights back unless you are having a problem. I have been running my fuge for 2 years on 27/7--im not about to switch, i have not reason too. and i have 7 species of macro algea

jabrams you must be on New York time to get the extra three hours per day.

 

[jabrams]

lol


must be typing to fas again. :roll:

 

[Nelliereefster]

FWIW,
I run 24/7 when establishing a new colony. I maintain 24/7 on smaller fuges (in relation to bigger tanks) and 24/7 for higher boiload systems.

I have never witnessed a "going sexual" event. But many data points here suggest it's no big deal anyway...

As a general maintenance step, I keep caulerpa cropped back to a 4-8 inch "turf" and keep fairly good water circ going in my fuge. (about 1500 gallons per hour flow through my 80 gallon fuge)

BTW, great thread, and good to see so many people use the fuge idea.

My vote, 24/7, but 16 on, with overlap to main reef lights, and a dark period has worked well for me also.

 

[brandon4291]

What a great thread Louey, Im a little late jumping on the bandwagon as I didnt see this until now.

My thoughts:

All anecdotal observations, but just like Jimmy I have seen my grape algae stay healthy for a year now being lit continually. It did crash once when under the 12/12 trial.

I am under the impression that the dark phase is an optional phase in photosynthesis, and the dropping growth curve we see in side-by-side trials is due to the 24x7 side consuming all available CO2, hence the slow growing compared to the plant who can build up CO2 stores for the next day through nightime respiration. Did we try the experiment while feeding CO2 continually to the lighted test Dr. Reef? My setups (sealed reefs with no gas exchange) must process continual CO2 production and I feel this is just the fuel needed to keep growth strong without crashing...

Just an idea, great thread guys. Ill vote now!

 

[Anonymous]

I forgot about this thread. I see that I changed to reverse photoperiod about a year ago and still keep it that way today. I recently increased the refugium photoperiod so that it overlaps the main tanks photoperiod by about an hour on each end. I did this to see if the extra photoperiod would force the caulerpa to consume enough additional nutrients so that cleaning the glass in the main tank could be done less often. This did make a small difference, but not much.

On another note, my refugium no longer sucks like I said it did a year ago. It just takes time for the macros to take off. It is now packed from wall to wall with macros and bugs. I was just being impatient when I made that comment.

I still have never had any problems with macro's going sexual. Knock on wood.

Louey

 

[Anonymous]

Well, if algae can be lit 24/7, why don't we just light our main tanks all day and night too! 8O

 

[klingsa]

Ok, I also have not read this thread until now, but I do have some thoughts on the matter. I am a biologist, and have taken a course on Phycology, the study of algae. With that said, I do not consider myself an expert. This is just from what I have learned.

The one issue that I believe no one has addressed is oxygen toxicity. We all know that the longer photosynthesis is performed, the more oxygen produced. Buildup of oxygen is toxic to cells. If the photoperiod is extended, perhaps this is the cause of additional stress which makes the algae go sexual.

I do agree that sexual reproduction is triggered by stressful conditions. I think it has been scientifically proven, plus it makes sense, at least to me. When an organism is in danger, it will want to pass on its genes as quickly as possible. This has nothing to do with being sentient, since evolutionary advances are based on natural selection.

The discussion about differences between vascular plants and algae does not make sense to me. It doesn't matter if they are physiologically the same or different. The similarity that matters is the cloroplast, which has very similar structure in both groups. The same pigments are used, with the same result.

The dark phase of photosynthesis (Calvin Cycle) is not optional. It is the conversion of sugars into ATP, chemical energy. The ATP is used during cellular respiration, as is the oxygen. All are happening constantly in algae and plants, except for the photosynthesis, which of course only happens when light is available.

The question about Alaska is a good one. Actually, the algae that live in such environments are the same that live elsewhere. It has simply adapted to variable photoperiods. The question is, can they make enough sugars to produce enough energy to perform cellular respiration. Obviously they can. It could very well be that at seasonal changes, sexual reproduction is triggered, for the same reasons it is seen in refugiums.

Sorry for the length, but there were 4 pages to comment on!
Sara

 

[Minh Nguyen]

I think I should point out that the Dark phase of photosynthesis in not optional, but it can happen during the day also. The dark phase (I think it is mis-named) does not require light, but it does not require darkness.
I light my refugium with two 250 W MH in reverse light cycle. My algae only go asexual when it is overcrowded. If I prune my refugium regularly, it never goes asexual.
Minh

 

[brandon4291]

How is the caulerpa surviving in the tanks who do light it 24x7? I still think it has to do with a steady production of CO2 from respiration in the front tank, especially in systems that contain fish and produce waste gas 24x7. The oxygen production can continue without a slowing until this vital fuel is used up...Im sure if you measured it accurately there are peaks and troughs in the net O yield from a 24x7 refugium, as the day-cycle main tank will also compete for CO2 during its photoperiod (zooxanthellae need it, unseen algaes and any photosynthesizers will use it).

There has to be a reason why macros will survive and thrive with continual lighting, maybe they are very adaptive? What would happen if we lit our tanks 24x7? I dunno, corals can retract to alter lighting on their tissue so maybe it wouldn't hurt. Would there be algae outbreaks not found if the main display wasnt lit 24x7? Sometimes people report their lighting timers going out on a vacation, and coming home to pea-green soup. Still algae is a function of systemic nutrients so thats up in the air...

I wouldn't worry about oxygen toxicity when generated from natural sources, ie photosynthesizing plants. In these 24x7 systems they are not running at full speed all the time, only when the display tank is in a night phase would the refugium produce at its max.

When the water reaches saturation, the excess O will form microbubbles and float up to the top. The only way to toxify water with O is to pressurize it in some way which we aren't doing. If cellular oxygen toxicity were a problem, the ones who do light their refugiums 24x7 for years would not have such plant/macro success. Im just ranting here, but what else can the explanation be? Matt has already adjusted my scheme on the concept of nitrogen and nitrate, so if my photosynthesis scheme needs adjusting Ill take that as well!

 

[jordanphulet]

Cant forget the dark cycle of photosynthesis.

 

[klingsa]

Brandon429 wrote:

I wouldn't worry about oxygen toxicity when generated from natural sources, ie photosynthesizing plants. In these 24x7 systems they are not running at full speed all the time, only when the display tank is in a night phase would the refugium produce at its max.

Hmm...I guess I don't understand the idea behind alternating photoperiods very well. Never had a refugium, so that would be why. How does the lighting of the main tank affect the production in the refugium? Because of nutrient production and consumption? If someone could straighten me out here, I'd certainly appreciate it.

I do agree, Brandon, that algae are extremely adaptable, and that must explain why people have such varied success. I'm certainly not saying that a 24/7 photoperiod is BAD for the algae, since people's experience clearly shows that this is not true. What you said about oxygen saturation of the water is true, but I was thinking more along the lines of toxicity within the algal cell. Before it is released into the water, that is. I see what you're saying, though, that they would just release it before it got to a toxic level. Perhaps...it was just an educated guess.

I think that if we lit our main tanks 24/7, after a certain amount of time, things would adjust. We know that corals produce accessory pigments to protect them from overexposure. I guess it's a question of what might die before it is able to adjust. As Brandon said, though, there are peaks and troughs in photosynthesis, so I don't think it is a foregone conclusion that microalgae would multiply much faster than it does under a 12 hour photoperiod. I believe there is correllation between photoperiod and growth rate, but it is not necessarily a causitive relationship. If that is true, which it may not be, then a reduced photoperiod as a way to control algae blooms does not make sense. Actually, if algae are indeed so adaptable, then it seems to me that they would actually be at an advantage with a lowered photoperiod. Zooxanthellae and animals competing for nutrients cannot adapt as quickly so the algae would have only our artificial means of filtration to hold it back. This is an interesting question, IMO, and I plan on taking it to my Phycology professor at the end of the month. If he doesn't know, I may set up an independent study experiment. That's my kinda fun! :lol: What do you guys think?

Sara