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Does lighting have to be synced with daylight hours?

bushaaayyy

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25 Dec 2020
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I’m wondering if you need to have my lighting schedule kept roughly in line with natural daylight hours?

I see a lot of recommendations for light cycles of around 6-8 hours. Most of the time I’d have to observe/enjoy my tank will be in the evenings. Would be nice to have the tank lit up for this time, would there be any problems caused if I run the light cycle from say 3pm to 10pm?

The tank will be positioned in the corner of the room opposite a north facing bay window, so won’t be getting much/any direct sunlight.
 
Not as far as I know, seems very common to run the lighting schedule to suit observing the tank. Sometimes with breaks in between. I run mine for a couple of hours in the morning, on again later in the afternoon and off in the evening. This works well with feeding and allowing the kids to see the tank! In one of George Farmer's videos he calls this the 'Siesta Method', which apparently some people think helps reduce algae (not sure if this is true or not!), but then goes on to say he always runs his lighting period straight through with no break.
 
The recommended 6 to 8 hours cycle is more aimed towards the best period to prevent algae but still sufficiently grow plants. It's a sort of better safe than sorry, lazy men's concept without guarantees... It's a good schedule for a start since most plants need to transition to aquatic form and establish... Then if this works well or sufficient enough then why change a winning team?

But that all doesn't mean this approach is a rule written in stone... If you look at nature in the tropics than we have about a 12 hour light cycle all year round. And in our northern hemisphere, we have summers with an 18 hour daylight period. And it is quite well possible to grow plants and not suffer algae plages in 18 hour light cycles.

The later might be a tad far fetched for a high tech high-intensity lit aquarium... But since it is possible nowadays to use programmable light controllers, then even in high tech setups, when a tank is fully matured and established we can do quite well with 12 hour period with sunrise and sunset schedules with only a 6-hour period at the highest intensity and the first and last 3 hours at a lower intensity.

Stretching these boundaries is experimenting and researching with the need to be more actively involved with monitoring adjusting and maintaining to find that sweet spot in its stability... :) Since aquariums are extremely diverse and dynamic, things such as stocking, plant species and density play a major role...

I've experimented with light intensities bellow the plant compensation point and it can work quite well, plants sleep at these intensities but it's still lit enough to see what's going on in the aquarium. It gives a twilight ambience that also can work positively on fish behaviour. In nature, they will also have dusk and dawn what influences their behaviour. It can be very interesting to mimic and observe this in aquariums.
 
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Since we grow aquatic plants vegetatively, we can pick any schedule regardless of natural daylight cycle. But if we grow plants for reproduction, the wrong schedule can affect flowering, fruiting and seeding production.

I provide 4 hour lighting in the morning, and 4 hour in the evening to fit my viewing and feeding schedule with bright ambient light to moving sunlight in between. If I were to grow tomato plant indoor with that schedule, I may never see tomato.
 
Great info everyone thanks for the input

I've experimented with light intensities bellow the plant compensation point and it can work quite well, plants sleep at these intensities
Is there a general figure at which point the majority of plants will ‘wake’? Like a certain number of lumens
 
Is there a general figure at which point the majority of plants will ‘wake’? Like a certain number of lumens

I actually don't know, but if there was it probably will not be in lumens but in mol etc.... Lumens is not scientific but a figurative household number that actually says very little. I have had lights that had higher factory specs in lumen but were less bright than the so-called lower rated. Thus lumen specs are you can't argue with the label without professional equipment. How can you know?

Next to this it highly depends on the plant species, take for example Anubias, named after the Egyptian god of the underworld. This plant almost grows in the dark. There are scientific papers on the internet with LCP data on several aquatic plants. Unfortunately, i lost track of where they are, but i know these papers have been posted here on the forum in the past.

Anyway, regarding ambient light, you can go pretty low with very dim light and still see your fish... Theoretically, i had 3500 lumen total and dimmed this to 5% and still was able to view everything. Thus you need very little light especially when the room your in isn't that bright. What makes a tank or glass in a general dark and mirroring is when the light in front is much brighter than behind the glass. But in the evening sitting in a fairly dimmed room, you need very little light above the aquarium to break through the natural mirror effect.

If you have an open-top tank you also could use a dimmed spotlight hanging above it to the wall. This can give a very nice moonlight effect shining into the tank from an angle from a distance casting interesting shadows. And not stress the plants...
 
Plants have no brain or neuron so they don’t go through sleep and wake cycle like animal. But plants have memory and will change in behavioral, hormonial, and biochemical processing in response to diurnal and seasonal stimulI.
 
Plants have no brain or neuron so they don’t go through sleep and wake cycle like animal. But plants have memory and will change in behavioral, hormonial, and biochemical processing in response to diurnal and seasonal stimulI.

Circadian rhythm - Wikipedia :)

How plants perceive their surroundings yet is totally unknown but there is quite some evidence that they absolutely do to a certain extend. For a very long time, it was believed that anything living needs brain tissue to have whatever form of intelligent perception or emotional awareness and mutual communication etc. Some scientists do believe plants have it all because they evidently do change behaviour accordingly when a certain external stimulus changes. How the plant does this and how it processed is yet for the biggest part a mystery.

It certainly points to the fact that we have overrated brain tissue for a very long time... Even for us humans we have enough evidence that it ain't all in our brain/head.
 
been known for a while they can communicate with each other, smell of a cut grass for instance alters other grass near by and they can also share resources via their roots and the fungal mass that connects them @dw1305 might have some papers on just how complex their world is proving to be
 
Great info everyone thanks for the input


Is there a general figure at which point the majority of plants will ‘wake’? Like a certain number of lumens
After a cursory look at some circadian info the simple answer would be to maintain a 24 hr period.
8 on 16 off ect not like 6 on 6 off and repeat
Not sure how it would effect things since not all species behave the same way circadian wise.

Circadian rhythms kind of change the concept of waking up but from one standpoint plants have a point where dark reactions ( respiration and btw also occurrs in the light) exceed light reactions to cause a negative food intake.
I'd consider the waking point as to when co2 intake exceeds out take ;)

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After a cursory look at some circadian info the simple answer would be to maintain a 24 hr period.
8 on 16 off ect not like 6 on 6 off and repeat
Not sure how it would effect things since not all species behave the same way circadian wise.

Circadian rhythms kind of change the concept of waking up but from one standpoint plants have a point where dark reactions ( respiration and btw also occurrs in the light) exceed light reactions to cause a negative food intake.
I'd consider the waking point as to when co2 intake exceeds out take ;)

afd8wf2TIz3hcoQZ_bliaTPFf9l3gYx9kMPOyAso9NWyYHLnHA.gif
lighting for the 6 cycle must be also harder for a lot of animals to deal with, seen folks live on 6 on 6 off (quite common for mariners) and they not having as good a time as some one on 12s with a bigger chance to rest or relax
 
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