Break from light?

[Emily M]

OK aquatic botanists...

I’m puzzled. If you break up your lighting during the day (4 h AM, 4h PM) can you prevent algae growth? 
 

I’m playing with the total light, nutrients, balance. Really fun actually, but now I’d like to consider light splitting. 
 

does it make a difference? 
 

Debate!

 

thx,

emily

[FrozenFins]

I would assume no. If your plants can grow in that lighting schedule then so could algae, right? If their still getting the 8-10 hours a day you'd think that algae wouldn't care and would grow anyway. Algae can also grow under other lighting, like the lights that are outside of your aquarium (like your room lights, window, t.v) All though these lights won't cause a HUGE algae outbreak but algae could still survive under those conditions.

Edited January 25, 2021 by James Black

[AdamTill]

If you search for “siesta” I think it’s been talked about a few times. My personal experience is that it doesn’t really help with algae, but can be nice if you want to see the tank before and after work.

[Emily M]

Thx for the feedback!!!

[gardenman]

I'd be very surprised if it made a difference in algae growth. It could have unintended consequences on the tank's environment. People get affected by day length with depression being more common in months with shorter days. You may have heard of Seasonal Affective Disorder or SAD.  Nature is designed around our natural diurnal/circadian cycle. When you vary that by too much, it throws things off. By having essentially two days and two nights each day you would likely cause some interesting disruptions in things. "Fish wouldn't care. They don't have emotions." If you've ever kept an Oscar you'd know that at least some fish have emotions. Oscars are kind of the divas of the fish world who will sulk over pretty much anything that upsets them. They're more outwardly expressive than other fish in their emotions, but levels of cortisol in the water tend to rise when fish are stressed. Even the supposedly emotionless fish.

In land based plants there's the rhizosphere where air and soil meet and much of what happens there is affected by daylength. (And lots of interesting stuff goes on in the rhizosphere.) I would assume the water/soil boundary contains similar bacteria and micro-organisms and altering their behavior by altering day length in a drastic fashion could have an unknown impact on that rhizosphere that could affect tank health. When humans are deprived of all outside knowledge of time they tend to develop a 25 hour circadian rhythm instead of the "normal" 24 hours one. A few go into a 48 hour circadian rhythm. There would likely be an unintended effect on your fish and plants if you went with two daylight cycles per day.

I'm more of a set and forget kind of fish-keeper. My lights come on at six in the morning and go off at nine at night. Conveniently, that's the time I'm awake and watching my fish. (My plant lights for my terrestrial plants come on at five in the morning and go off at nine at night, so they get an even longer day.) In a perfect world my lights would follow the daylength of the calendar where the fish originate along with the water temperature variations from day to night and seasonally. That would likely help trigger breeding and seasonal activities.  I'm not that crazy (at least not yet) but that would arguably be the ideal.  Lacking that initiative, I tend to just go for stability. It works for me. I would be very nervous about the unintended consequences of having two day/night cycles per day. I don't think Algae would care, so I don't really see an upside to it.

 

[Daniel]

For what it is worth George Farmer does not think a siesta makes a difference with algae.

[Socqua]

Lighting is discussed at great length in the Fluval 3.0 thread:

From @Streetwise in that thread:

Quote

Siestas are great. From what I understand, plants ramp up photosynthesis faster than algae.

I don't have any personal experience to share, but that sounds plausible at least! Just my gut tells me that slight differences in lighting doesn't cause any sort of SAD; Terrestrial plants outside regularly get cloud coverage and varying amounts of sun day to day and even hour to hour. Generally more sun = more photosynthesis = more growth, but there is certainly no one size fits all here... Some plants die if they get too much sun.

Also, @gardenman, regarding your last sentence, "I don't think Algae would care, so I don't really see an upside to it," I'm curious why having a siesta ("two day/night cycles per day") would have consequences for plants, but not for algae? Just curious.

edited to add (after just now seeing Daniel's post before mine): Forget everything I just said and listen to Daniel 😄

Edited January 26, 2021 by Socqua

[gardenman]

1 hour ago, Socqua said:

Lighting is discussed at great length in the Fluval 3.0 thread:

From @Streetwise in that thread:

I don't have any personal experience to share, but that sounds plausible at least! Just my gut tells me that slight differences in lighting doesn't cause any sort of SAD; Terrestrial plants outside regularly get cloud coverage and varying amounts of sun day to day and even hour to hour. Generally more sun = more photosynthesis = more growth, but there is certainly no one size fits all here... Some plants die if they get too much sun.

Also, @gardenman, regarding your last sentence, "I don't think Algae would care, so I don't really see an upside to it," I'm curious why having a siesta ("two day/night cycles per day") would have consequences for plants, but not for algae? Just curious.

edited to add (after just now seeing Daniel's post before mine): Forget everything I just said and listen to Daniel 😄

The reason I say that is because of the rhizosphere that plants have where in terrestrial plants air and soil meet, is full of life and photo sensitive and reacts to day lengths. Longer days makes the rhizosphere more active resulting in more nitrogen fixation and activity. Assuming aquatic plants have a similar zone where water and soil meets then that could also be sensitive to day lengths. Algae isn't soil dependent and will pretty much grow anywhere on anything, so day length should be less of an issue for it. Also, fairly or not, I think of algae as more primitive and survivable. Getting algae to grow is typically very easy. Stopping it from growing is more of a challenge. I don't think the algae would care if it was getting two four hour bursts of light. Does algae form a sort of rhizosphere on whatever it attaches to? Maybe. I've never heard of it doing so, but it could. I do know that terrestrial plants are affected by day length however. By and large what affects terrestrial plants, affects aquatic plants 

[Ben_RF]

Swapping to a seista style actually helped me to finally overcome greenwater after years in one tank.  I was doing 9 hours straight.  Swapped over to the seista of 4 hours on, 4 hours off, and 5 hours on and the green water went away in a few weeks.  

I have tried it with my other tanks, and honestly not really seeing any real benefits.  

[Streetwise]

This is another thread where we discussed the topic: