Argument against reverse lighting cycle on a refugium

[Ocelaris]

So what do we get for the reverse lighting cycle, a little pH bump? But if we're growing macro algae, isn't most of the food being decomposed from ammonia during the day? So we're left with whatever remnants of nitrogen at the end of the day. Sure nitrate uptake will happen overnight, but wouldn't it be better to have the macro algae compete with the nuisance algae during the day? I can see if you have no algae in the tank to running a reverse daylight cycle, but really is a small pH bump worth the competitive disadvantage of higher nutrients during the night?

Thoughts?

 

[Crabs McJones]

So what do we get for the reverse lighting cycle, a little pH bump? But if we're growing macro algae, isn't most of the food being decomposed from ammonia during the day? So we're left with whatever remnants of nitrogen at the end of the day. Sure nitrate uptake will happen overnight, but wouldn't it be better to have the macro algae compete with the nuisance algae during the day? I can see if you have no algae in the tank to running a reverse daylight cycle, but really is a small pH bump worth the competitive disadvantage of higher nutrients during the night?

Thoughts?

I'm interested to see how this plays out. The main reason I was told about the reverse cycle was to reduce the ph swing. Interested to see what others say

 

[saltyfilmfolks]

I would grab an inexpensive pinpoint meter and find out how high the “bump” is.
Every tank will be different.
(Coral load, macro load, dosing schedule, number of people and pets in the house )

But IMO , bump is incorrect, it’s actually just stopping it from falling, boost or stabilizer may be a better term

I have one sumped/fuged and one non sumped .

 

[KMench]

I would agree that your argument makes sense, but when a tank has ~0 nitrate and ~0 phosphate does nutrient export trump pH control?

 

[flagg37]

I tried a while back to have the sump light go on every time the tank ph dropped below a certain point in an effort to lessen the ph swing but it seemed to throw off the normal cycle peaking at weird times and not consistent so I went back to lighting it opposite the display lighting. I know some of our local club members are lighting their fuge almost 24 hours a day. They’re not concerned with the ph but getting as much nutrient export as possible.

 

[Ocelaris]

My pH rise due to the reverse cycle was basically non existent (Apex monitoringl, but that's with weak lighting and a small amount of chaeto, so I agree, it varies drastically for everyone. If you're already at a low nutrient levels, the pH rise may be more beneficial, but I was trying to poke holes in my argument.

The basic argument is that macro algae would be better served to reduce nutrients when the tank lights are on if you have algae in the tank, otherwise a reverse cycle would be more helpful.

That brings up another point, does algae also have some requirements for a dark cycle, aka the Krebs cycle? I would assume so, but having it on all the time wouldn't really help minimize pH swings as you'd always get that increase.

 

[Mal11224]

I recently reduced my fuge lighting cycle. Used to run it from 2pm - 10am thinking it would help stabilize my PH, which it believe it did but I wanted to see what the affect would be to my PH if I ran it from 6pm to 9am when my lights come on and my PH actually dipped by 0.2 but rose by 0.5. Very interesting.
Previous range = 8.13 - 8.27
After adjustment = 8.11 - 8.32

 

[S.O.MLemos]

Plants feed off nutrients 24 hours a day even when it’s dark. I’m new to this hobby but I grow 8ft tomato plants as well as some other monsterous things and I only feed/fertilize just before dark. Macro is a plant so in my opinion I don’t think it matters other than the PH change from day to night. Again I’m fairly new so feel free to ignore this especially since I’m comparing a dirt plant to a water one.

 

[NY_Caveman]

I tried a while back to have the sump light go on every time the tank ph dropped below a certain point in an effort to lessen the ph swing but it seemed to throw off the normal cycle peaking at weird times and not consistent so I went back to lighting it opposite the display lighting. I know some of our local club members are lighting their fuge almost 24 hours a day. They’re not concerned with the ph but getting as much nutrient export as possible.

It is my understanding that macroalgae, and plants in general for that matter, need a dark period of at least 4-6 hours. They will still grow as many have tried this, but grow faster and stronger with some dark period.

This is more scientific (but older, 2006):

“Photosynthesis of Algae in Continuous Light vs. Light/Dark Cycles
-Randy Holmes-Farley

Interestingly, three marine microalgae, Skeletonema costatum, Phaeocystis globosa and Emiliania huxleyi,24 were studied for their rates of photosynthesis and carbon uptake mechanisms in continuous light vs. those same species in light/dark cycles (12 h on/12 h off and 16 h on/8 h off). The rates of photosynthesis were nearly twice as high with light/dark cycles as with continuous lighting. In two of the species (S. costatum and E. huxleyi), but not the third, the contribution of bicarbonate to the total carbon uptake increased dramatically in light/dark cycles compared to continuous light.

How this result might relate to growth and nutrient uptake in lit refugia where macroalgae are often grown to export nutrients is not known. However, it is a sign that perhaps continuous light is not optimal, in addition to being more expensive.”

http://reefkeeping.com/issues/2006-10/rhf/index.php#13

 

[dragon99]

Why would food only decompose during the day? It's decomposing constantly in whatever crevice it gets stuck. Also fish release ammonia around the clock.

 

[Mombo]

I am planning on running my Fuge 12 hours. My main lights are on 14 hours. So they will overlap only when the DT is at the low point of its on/off schedule.

 

[NY_Caveman]

I should note I just searched and found this that Randy posted in another forum (I am not posting the link as it is another forum). This was two years after the above article I posted and feel I should mention it to be complete:

“Do they just adjust to perform light cycle and dark cycle functions simultaneously?

What functions are you referring to? The observation by lots of people is that many species of macroalgae thrive under 24/7 lighting. Exactly what biochemical changes this might entail isn't clear from hobby experiments, but I will point out that many photosynthesizing organisms live in 24/7 sunlight, such as in high latitude summertime. ”

I must say I always thought plants in general needed a dark period. During the dark period they respire (take in oxygen to create energy from the food they produce). This process creates CO2. This is basic, but I personally do not know the specific effects if there is no dark period. Maybe @Randy Holmes-Farley can chime in tomorrow.

 

[Lasse]

I think that the answer is not as easy as the first post indicate.

It’s true that NH4/NH3 release from the fish is directly through the gills then they get feed - there is a point - but is this the only NH4/NH3 source in a cycled and biological active aquarium? IMO It is not and not even the most important source. The most important source is instead the bacteria breakdown of organic matter – the mineralizing process – and its take place the whole 24-hour cycle. My fuge has a DSB with reversed flow just in order to give the macro nutrients 24/7. I run reversed light cycle and the reason is that during daytime – the corals need the NH4/NH3 produced by fish and bacteria and during night time the macro get NH4/NH3 from bacteria production and some nitrate if produced during nitrification (or by me through adding nitrate)

Its also true that some photosynthetic organism can store nutrients during night time and use them during the light period – if this is true for Chaeto (which I use) – I do not know.

I´m also convinced that all photosynthetic need a dark period if you look over time. Its also true that some plants (like some potatoe and at least some grains) – that normally need a dark period – grow as hell near or north of the Arctic Circle in Sweden. The daylight will last for more than 2 months up there. And the north Atlantic is very productive up there too. I think this is a question of species.

IMO it could be good of more than one reason (the pH thing) to run the fuge on reversed light - you will have two daytimes for different organisms (corals and macroalgae)- they need not to compete with each other

Sincerely Lasse

 

[hart24601]

Dark reactions are not that great of a name for reactions. The reactions can occur anytime and in the presence of light, they were just they don’t require light.

https://www.biology-online.org/dictionary/Dark_reaction

 

[Ocelaris]

So the question left to me is how long ammonia stays available in the aquarium, and I still believe feeding time would be the peak time, and it trails off after that. It's true fish put out ammonia and poop through out the day, but all the junk from frozen food is a significant nutrient input and isn't processed by the fish.

To me the dwell time of nutrients as they're broken down probably is how to determine whether the macro algae is best served by day or night. My assumption is that the nutrients are processed rapidly, like within the hour. Ie broken down from larger organic molecules to the final inorganic nutrients which the plants take up. This is under the assumption that algaes also only absorb inorganic molecules like plants.

But these are assumptions, and if someone knows better, I'm all ears.

 

[Randy Holmes-Farley Verified Community Expert]

So what do we get for the reverse lighting cycle, a little pH bump? But if we're growing macro algae, isn't most of the food being decomposed from ammonia during the day? So we're left with whatever remnants of nitrogen at the end of the day. Sure nitrate uptake will happen overnight, but wouldn't it be better to have the macro algae compete with the nuisance algae during the day? I can see if you have no algae in the tank to running a reverse daylight cycle, but really is a small pH bump worth the competitive disadvantage of higher nutrients during the night?

Thoughts?

I'd personally stick with night cycle because of O2 primarily and pH secondarily.

Do you have any info suggesting how nutrients vary day to night? The scientific literature does not seem to support more ammonia excretion during the day.

I don't think we have much good information on the ammonia levels through the day and night in any reef tank (I am hoping the Mindstream device provides reefers with some info in this regard). Moreover, I do not think there is any information that suggests that reef tanks in general have issues with ammonia being undesirably high at any time of the day or not.

This paper studying salmon shows more ammonia release at night (Figure 4):

https://www.sciencedirect.com/science/article/pii/014486099190015C

"Generally, the oxygen consumption was highest in daylight when the fish were feeding, and the ammonia excretion exceeded peak level in the evening-night period several hours after feeding had ceased."


While these are unusual fish (air breathing freshwater fish), they excrete ammonia pretty evenly 24 h a day (day = night) (see Table 4)

http://shodhganga.inflibnet.ac.in/bitstream/10603/60823/7/07_chapter 1.pdf

 

[Ocelaris]

Do you have any info suggesting how nutrients vary day to night? The scientific literature does not seem to support more ammonia excretion during the day.

My wife and I both have seen the fish poo at night, but never during the day. Does that count as peer review?

I was just thinking that having the macro algae competing at the same time would be more effective at limiting in tank algae. It would be a good brs video for their chaeto tests.

 

[saltyfilmfolks]

My wife and I both have seen the fish poo at night, but never during the day. Does that count as peer review?

I was just thinking that having the macro algae competing at the same time would be more effective at limiting in tank algae. It would be a good brs video for their chaeto tests.

“BRS Invesitgates!: Fish Poo”

 

[Danny Venditti]

I'd personally stick with night cycle because of O2 primarily and pH secondarily.

Do you have any info suggesting how nutrients vary day to night? The scientific literature does not seem to support more ammonia excretion during the day.

I don't think we have much good information on the ammonia levels through the day and night in any reef tank (I am hoping the Mindstream device provides reefers with some info in this regard). Moreover, I do not think there is any information that suggests that reef tanks in general have issues with ammonia being undesirably high at any time of the day or not.

This paper studying salmon shows more ammonia release at night (Figure 4):

https://www.sciencedirect.com/science/article/pii/014486099190015C

"Generally, the oxygen consumption was highest in daylight when the fish were feeding, and the ammonia excretion exceeded peak level in the evening-night period several hours after feeding had ceased."


While these are unusual fish (air breathing freshwater fish), they excrete ammonia pretty evenly 24 h a day (day = night) (see Table 4)

http://shodhganga.inflibnet.ac.in/bitstream/10603/60823/7/07_chapter 1.pdf

Have there been any updates on the Mindstream as it seems to be a never ending waiting game.

 

[Randy Holmes-Farley Verified Community Expert]

Have there been any updates on the Mindstream as it seems to be a never ending waiting game.

I have not seen any recent public updates.