Argument against reverse lighting cycle on a refugium

[jason2459]

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

Interesting. My experience with ammonia measurements from my tank support the salmon research.

I've also flound it very interesting to see my ammonia goes up to 0.01ppm and back down to 0.001ppm every day with a steady up swing through out the day to midnightish and a steady down swing after that.

From:
https://www.reef2reef.com/threads/s...blished-tank-i-think-not.258297/#post-3054386

 

[Forsaken77]

Are there not nutrients at night time?

Imo, I also think it's better for certain macro to indirectly compete with micro algae because the micro algae may uptake more nutrients being it's directly in the DT where the nutrients are coming from. The macro may not work optimally in that scenario.

The biggest problem, again imo, is that you would then have all algae consuming oxygen at the same time, night. This could deplete the tank's air much faster for fish being the DT's lights are off more than they're on. With all algae on the same photo period, it could cause an even bigger drop in Ph overnight.

With a reverse period, at least you have the macro giving off oxygen when the micro is giving off CO2.

 

[jason2459]

Are there not nutrients at night time?

Imo, I also think it's better for certain macro to indirectly compete with micro algae because the micro algae may uptake more nutrients being it's directly in the DT where the nutrients are coming from. The macro may not work optimally in that scenario.

The biggest problem, again imo, is that you would then have all algae consuming oxygen at the same time, night. This could deplete the tank's air much faster for fish being the DT's lights are off more than they're on. With all algae on the same photo period, it could cause an even bigger drop in Ph overnight.

With a reverse period, at least you have the macro giving off oxygen when the micro is giving off CO2.

Algae doesn't deplete oxygen but just the opposite. Bacteria however could.

And pH is directly related to CO2 not Oxygen levels. So, again the algae would help there in consuming CO2.

 

[Scrubber_steve]

Plants produce CO2 (Carbon dioxide) all the time as a metabolic product of respiration, but when light is available, they can use and fix some of this CO2 as a substrate in photosynthesis. When light is available, they also take up additional CO2 from the surrounding atmosphere, and one of the the end products of photosynthesis is O2 (molecular oxygen), so when light is available, on net balance they use/fix more CO2 into other molecules than they produce, and so produce more O2 than CO2.

When light is not available, i.e. when it is dark, they do not have an energy source for photosynthesis, and so cannot fix CO2 and produce O2, but of course they must continue to respire to stay alive (and hence continue to produce CO2), so they become net producers of CO2.

Depending on the species of plant and the environmental conditions, most plants are net fixers/users of CO2 and producers of O2 when averaged out over the course of a light/dark photoperiod (usually 24 hours).

 

[Scrubber_steve]

I doubt that there is anywhere near enough microalgae in a normally functing aquarium to make any dent in o2 - co2 levels

 

[Scrubber_steve]

I have algae illuminated 24/7 in my tank.

 

[Ocelaris]

@Scrubber_steve

Do you have an opinion on nutrient uptake during light VS. Dark cycles? I have seen the light/dark cycle and photo period debate for over a two decade span and can't say I'm swayed strongly either way as each type of photosynthetic organism reacts differently to photo period. I still will probably keep a slightly reverse cycle for temperature reasons, but otherwise it doesn't seem to make much of a difference.

 

[Scrubber_steve]

@Scrubber_steve

Do you have an opinion on nutrient uptake during light VS. Dark cycles? I have seen the light/dark cycle and photo period debate for over a two decade span and can't say I'm swayed strongly either way as each type of photosynthetic organism reacts differently to photo period. I still will probably keep a slightly reverse cycle for temperature reasons, but otherwise it doesn't seem to make much of a difference.

I browsed through a couple of papers a while back, both to do with using algae filtration, one on a prawn farm set up, & the other something similar from memory. Both stated that take up of ammonia continued during the dark cycle, but to a lesser extent as when the algae was illuminated.

 

[Sir Chris]

I run mine for 10 hours. I have Pom Pom and Chato. My Pom seems 2 b getting white now and was running it 17. And no issues so I’m not sure if there’s a higher demand.. they are still free floating and are they I need 2 place them in my marine pure 2 root?...

 

[Ocelaris]

I browsed through a couple of papers a while back, both to do with using algae filtration, one on a prawn farm set up, & the other something similar from memory. Both stated that take up of ammonia continued during the dark cycle, but to a lesser extent as when the algae was illuminated.

Thanks, that's what I was looking for!

 

[jason2459]

Plants produce CO2 (Carbon dioxide) all the time as a metabolic product of respiration, but when light is available, they can use and fix some of this CO2 as a substrate in photosynthesis. When light is available, they also take up additional CO2 from the surrounding atmosphere, and one of the the end products of photosynthesis is O2 (molecular oxygen), so when light is available, on net balance they use/fix more CO2 into other molecules than they produce, and so produce more O2 than CO2.

When light is not available, i.e. when it is dark, they do not have an energy source for photosynthesis, and so cannot fix CO2 and produce O2, but of course they must continue to respire to stay alive (and hence continue to produce CO2), so they become net producers of CO2.

Depending on the species of plant and the environmental conditions, most plants are net fixers/users of CO2 and producers of O2 when averaged out over the course of a light/dark photoperiod (usually 24 hours).

Are you saying algae is a plant?

For clarification, my statement was in reference to lighted periods.

 

[Gareth elliott]

https://www.google.com/amp/s/www.scienceabc.com/nature/do-plants-and-trees-sleep.html?isamp=1

This is about terrestrial higher plants. There was a study i think in japan where higher plants eventually wither without daily rest periods.

But higher plants have giant genomes. A lotus having 45,000 2x as many as homosapiens.
Some algae that have been sequenced range from 7000-18,000. So there is a lot of genetic material that has been acquired since moving to more complex. So dont believe this study correlates.

 

[Sir Chris]

https://www.google.com/amp/s/www.scienceabc.com/nature/do-plants-and-trees-sleep.html?isamp=1

This is about terrestrial higher plants. There was a study i think in japan where higher plants eventually wither without daily rest periods.

But higher plants have giant genomes. A lotus having 45,000 2x as many as homosapiens.
Some algae that have been sequenced range from 7000-18,000. So there is a lot of genetic material that has been acquired since moving to more complex. So dont believe this study correlates.

I grow and u need a night rest for energy 2 metabolize from sun into sugars during the day they absorb during the night that collected energy then goes into it like food into our stomachs so when that light comes on they are sprite and new growth. Most new growth on plants happens at night... and I grow fruiting plants tho... they have periods and life cycles as chato doesn’t as i can see. If u haven’t viewed any timelapse of plants it’s really fun. Now a ficus might work diff but I know how a plant designed 2 flower then die or fruit.

 

[Randy Holmes-Farley Verified Community Expert]

how does it work in nature? Do the algae on the reef have a different schedule than the rest of the flora?
Preventing the natural ph swing - is probably not beneficial - or is it? (I guess that is the question).

If the pH gets low at night, it is beneficial to raise it.

 

[Randy Holmes-Farley Verified Community Expert]

https://www.google.com/amp/s/www.scienceabc.com/nature/do-plants-and-trees-sleep.html?isamp=1

This is about terrestrial higher plants. There was a study i think in japan where higher plants eventually wither without daily rest periods.

But higher plants have giant genomes. A lotus having 45,000 2x as many as homosapiens.
Some algae that have been sequenced range from 7000-18,000. So there is a lot of genetic material that has been acquired since moving to more complex. So dont believe this study correlates.

Refugio do fine (IME) lit 24/7, but I eventually settled on less lighting time due simply
to lower electricity cost.

 

[MnFish1]

If the pH gets low at night, it is beneficial to raise it.

How low - and why? I thought this was discussed before - that there was no real difference in coral growth as long as the pH rose above 8.2 during the day. Though it may 'even out' the pH swing, during the day - the algae (not lit) will be net producers of CO2 - which will tend to lower the pH. (I personally leave my macro-algae lit all the time) - in the hopes of having a higher pH during the day - and a higher pH during the night. The 'swing' doesnt seem to harm anything (IMHO)

 

[MnFish1]

I grow and u need a night rest for energy 2 metabolize from sun into sugars during the day they absorb during the night that collected energy then goes into it like food into our stomachs so when that light comes on they are sprite and new growth. Most new growth on plants happens at night... and I grow fruiting plants tho... they have periods and life cycles as chato doesn’t as i can see. If u haven’t viewed any timelapse of plants it’s really fun. Now a ficus might work diff but I know how a plant designed 2 flower then die or fruit.

There are certain plants that need darkness to bloom - and there are certain plants that bloom better with 24 hours of light. I don't think you can generalize the way you are to algae. All the data I've seen suggest that growth in algae is dependent on 'light'.

 

[Scrubber_steve]

There are certain plants that need darkness to bloom - and there are certain plants that bloom better with 24 hours of light. I don't think you can generalize the way you are to algae. All the data I've seen suggest that growth in algae is dependent on 'light'.

This is from an article by Randy. It concerns micro algae but I can't see why it wouldn't apply to macro as well.
"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."

 

[MnFish1]

This is from an article by Randy. It concerns micro algae but I can't see why it wouldn't apply to macro as well.
"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."

OK - but - you keep your macro algae lit 24/7 right? I wonder - is the rate of photosynthesis calculated only when the light is on - or is it calculated on a 24 hour average basis. Sorry I dont have the reference - so im not questioning its accuracy - but if its only calculated when the light is on - it wouldn't make any difference.

 

[Scrubber_steve]

OK - but - you keep your macro algae lit 24/7 right?

Not exactly. I have two seperate screens.

I wonder - is the rate of photosynthesis calculated only when the light is on - or is it calculated on a 24 hour average basis. Sorry I dont have the reference - so im not questioning its accuracy - but if its only calculated when the light is on - it wouldn't make any difference.

It would be over a 24 hour period

"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."