Alternate Lighting Hours?

[MuddyWaters]

Here's a question for you: I've been keeping my fish no somewhat alternating hours of light for at least a year- I just assumed as long as the fish and plants get x amount of light a day, it doesn't matter really when it comes on each day.

I typically have the light on from 2pm - 8pm EXCEPT for Tuesdays and Thursdays when I typically work from home (or did). My work from home schedule is much more random (and frequent) now, but that was what I set up and I've just left it that way. On Tuesdays and Thursdays I have the lights on from 10am - 5pm- an hour longer and 4 hours earlier.

Is this a big deal? I'd be surprised if the extra hour made a difference, but it hit me this morning that maybe the 4 hour difference twice a week throws them off.

NOTE: I haven't noticed any weirdness in the fish and they are all very happily living. I haven't had any die for strange unknown reasons (have had some die, but I know how I accidentally killed them- different story).

Thoughts?

 

[gwand]

Fish share the same light-dark circadian rhythm as mammals. I suggest your light-dark cycle be consistent.

 

[Mazain]

I just assumed as long as the fish and plants get x amount of light a day, it doesn't matter really when it comes on each day.

For planted tanks the norm is 8 to 10 hours of light (depends on the lumens and watts). Changing the hours from 2.00 p.m. to 10.00 a.m. is good for your plants. I would have done 10.00am to 5.00 p.m. from the start.
Fish has a different cycle unlike plants do. I dont think it makes a difference to the fish since they got rest from 8.00 p.m. till morning previously.

 

[Rusty_Shackleford]

I would agree, fish need a consistent day/night cycle jist as much as plants do.
I've seen peer reviewed papers that say fish need 10 hours of darkness for rest in a 24 hr period.

 

[TwoTankAmin]

My tanks all get a similar duration of lighting and the lights on each tank come on and go off for a similar number of hours, However, while all tanks get a similar amount of light, the actual times they come on and go off vary.

Since I am retired I tend to get up later than I did for most of my working life. i am also up later as well. So, I tend to have the tanks in my bedroom come on and go off later in the day than tanks elsewhere.

Also, some number of years ago I stopped using the tank lights in my pleco breeding and grow tanks except when I have to work in them. The rest of the time they are only subject to whatever light comes in vie the one large window in the space they are in. My thinking was that they are fish which tend to hide during the day and are more active at night. So, I assumed that they do not experience a lot of brighter lighing/ Yje exception would be for the younger fosh which need more veggie matter and have to head to shallower levels in order to get algae which is available whereas plants are not available deepers or in the faster water in the shallower parts of the Big Bend of the Rio Xingu. However, in shallower water they become potential prey for birds.

What does vary in terms of my tank lightng is how intense it is in any given tank. That is determined by the types of plants in the tank as well as how well planted the tank is. However, it is important that fish are able to find shade when they want/need it.

 

[FattyFish]

My tank is in our living room, and we don't close the curtains, so it's natural daylight at first. Then I turn my lights on at 9 am at 20%, 10 am at 40%, 11 am at 80%, and midday at 100%.
3 pm, I start ramping down to 80%. When I get to 6 pm, I'm at 20%, then the lights are off at 9 pm, which is when I normally go to bed. My light colours are daylight throughout; it's just the intensity I change. I have good plant growth and active fish.

 

[Mazain]

My tank is in our living room, and we don't close the curtains, so it's natural daylight at first. Then I turn my lights on at 9 am at 20%, 10 am at 40%, 11 am at 80%, and midday at 100%.
3 pm, I start ramping down to 80%. When I get to 6 pm, I'm at 20%, then the lights are off at 9 pm, which is when I normally go to bed. My light colours are daylight throughout; it's just the intensity I change. I have good plant growth and active fish.

This is a good stress free time laps for the fish ascending and descending lightings. However, I dont think most medium to high lighting plants would be healthy and lush with the ascending and descending lighting cycle. Plants naturally wake up when day light falls on the tank. IMO that's when I start to feed them with stable 10 hours of light.

 

[FattyFish]

The proof is in the pudding. See attached photos. I have taken screenshots of the images, as they have the date on them.
The first two show the left and right sides of my tank on 11th July; the rest were taken this morning. It's clear to see the plants have grown around 8 inches in around 2 weeks, so the lighting routine does not hinder my plant growth; however, I completely agree that if I were growing a harder/more difficult type of plant, my lighting routine and even my lights may not help. Just a note: I don't run any Co2; I do dose 1 cap full of API Leaf Zone once per week, which is way less than what the instructions state. Also, I never suffer from any algae.

 

[Mazain]

Wow, beautiful tank!

 

[GaryE]

Plants versus fish can be a problem (but wow, the plant side of the tank above is beautiful). I've learned with temperate aquatic plants I've collected in Canada that lighting period is of extreme importance. If I collect Ludwigia, Vallisneria or hornwort before the summer solstice, it can adapt and live for years in my tanks. If I get it after the longest day, how soon after the solstice becomes crucial. A plant that looks fantastic in an August lake will inevitably die in October, while a plant from the same spot collected in June when the light is long will still be thriving year round. There has to be a genetic kill switch activated by conditions.

So I'll bounce that out, aware that there's no reason for equatorial plants to have evolved those mechanisms. But fish? That 12 hours of sun you get at the equator has to matter. It certainly can affect the breeding of temperate species, though sunlight isn't the only variable. Temperature comes into play there too. I know the manipulation of lighting periods can be a breeders' trick.

Hey, I adapted to working graveyard shifts overnight and sleeping in the day at one point in my life. It came at a physical cost, but I could do it. I suspect fish are as adaptable. I run my tanks in staggered bands. Some lights come on at 7, and some at 10 so I can work on them mornings or evenings. But each bank of tanks has the same on off timing. And none of my fish work lit up overnight shifts...

 

[Mazain]

So I'll bounce that out, aware that there's no reason for equatorial plants to have evolved those mechanisms

In the tropics where I live mother nature has blessed us with eco-systems that even exotic or terestrial plants can adapt and survive the monsoon floods. Most of the plants in my aquarium comes from various parts of the islands of sri lanka and honestly the aqua plants that are sold are imported species. The native plants are not popular except for cryptos and ketala species.
The water plays a main role in sustaining and growing plants and keeping fish. So thats a minus in the check list when creating aquarium setups to last.
I'm maintaining a low-tech setup and I keep the light to a 7.00a.m. to 5.00p.m. time frame. The only challenge is when I rescape emersed to submerge plants, the tank eco-system reboot water hardness and ph. This takes a few weeks to cycle and provide new growth.