# lights on and off intervals



## misterchengmoua (Dec 22, 2005)

i was wondering if it would be possible for me to have the lights come on in the morning for about 5 hours then turn off, and then come back on later for another 5-7 hours without having any negative effects on my plants?


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## Astral (Sep 24, 2004)

I don't have an answer for you but:

My lights go on at around noon and shut off at about 10:30 in the evening. I'm not at home in the morning that way I can enjoy and view the tank into the night.

Frank


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## JaySilverman (Jun 19, 2005)

Mine come on at 1 in the afternoon and go off at midnight. This way I can enjoy the tank and do maintenance on it when I get home from work.


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## dennis (Mar 1, 2004)

Mine are on from 1-11 at 1.5 wpg and 3-8 at 3.2wpg. This gives me in a sense a high light tank with less high light maintainence

Haveing a dark period during the day probably won't hurt the plants much, it won;t help them though. Also, th eplants take a little time at a specific light intensity to really start photosynthesising. Adding darkness in the middle of thier day will only make the plants grow twice as slow, stressing them and allowing algae to get a foot hold in the tank. I would not recommend it.


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## AQUAMX (Jan 24, 2005)

Hi Dennis

Im having this sometimes heated discussion with friends at the moment. Seems alot of people are under the impression that a break in light during the day somehow reduces algae? I cant understand the logic. 
You say it actually causes stress and promotes algae by having a break.

Can you please explain this to me better

Thank you

Brad


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## Cavan Allen (Jul 22, 2004)

I thought Dennis explained it pretty well. Just when they're really getting going you shut off the lights? :???: 

Anything you do to make the plants grow better will hurt algae. Having a period of darkness in the middle of the day will not help the plants. It isn't natural and isn't necessary to prevent algae. It's really as simple as that.


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## BryceM (Nov 6, 2005)

When in doubt, look at how nature does it. The whole mid-day siesta thing is really debated, but it doesn't make any sense to me. I think the reason that it is popular is that you get to see the tank when you leave home in the morning and when you get home at night.

It would really be cool to simulate sunrise, noon intensity, and a slow, gradual sunset. Not so easy when dealing with fluorescents.


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## random_alias (Nov 7, 2005)

http://www.aquaticplantcentral.com/forumapc/showthread.php?t=1851&highlight=light+siesta

and search for "lighting period" "siesta" or "photoperiod". That's how I found this.


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## AQUAMX (Jan 24, 2005)

Thanks guys and Random

I agree that a break in lighting is non beneficial. I was just wondering on peoples thoughts.

Brad


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## cS (Jan 27, 2004)

misterchengmoua, are you turning the lights off during mid-day (1) to prevent algae ((i.e. the "siesta" theory) or (2) to maximize viewing time when you're home? If it's the latter, then you can simply have the lighting period start a bit later as suggested in the above posts. However, if you're doing it to prevent algae, then it's not going to be effective. There are far more productive alternatives.

With regard to your original question, I must respectfully disagree with Dennis and Cavan that turning the lights off during mid-day will be harmful to the flora, fearing that the plants will have a hard time initiating photosynthesis. However, I read somewhere (and I wish I can remember where so that I can reference it ) that plants start to photosynthesize within *seconds/minutes* when all the necessary components are present. A reaction time of seconds/minutes is, in my very humble opinion, negligible.

Notwithstanding, if you were to repeatedly turning the lights off/on every 10 minutes, then yes, I can see how that could be detrimental to plant growth. But I can't imagine how turning it on/off only twice daily would be harmful. Nonetheless, it would be interesting if you follow what you had suggested and report your findings. Some practical experience would be very helpful.  I have read numerous reports/debates on the effects (or the lack thereof) of the siesta period on algae; but I have not come across a single account of how the plants were affected it.

Of course, this is only my opinion and not based upon personal experience or research. It just "sounds" unlikely to me. :mrgreen: I would love to hear what you think.


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## random_alias (Nov 7, 2005)

I knew there something about peak photosynthesis occurring at or around the 6th hour of the photoperiod, here it is:

http://www.plantedtank.net/forums/showthread.php?t=21095&highlight=peak+photosynthesis


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## gnatster (Mar 6, 2004)

random_alias said:


> I knew there something about peak photosynthesis occurring at or around the 6th hour of the photoperiod, here it is:
> 
> http://www.plantedtank.net/forums/showthread.php?t=21095&highlight=peak+photosynthesis


I read that thread a few times and the only reference to peak photosynthesis occurring at or around the 6th hour of the photoperiod is in one of your posts random_alias. I've also heard. and I don't remember were that plants reach their full potential for photosynthesis within minutes of being illuminated. Guess we both need to go look and find references and what is accurate.


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## BryceM (Nov 6, 2005)

I think it would be an oversimplification to assume that the only thing that matters to plant health is achieving peak photosynthesis. I'm going out on a limb here, but I'd venture that there are many cyclical processes that occur in plants based on a natural 24 hour day. While photosynthesis is a relatively straightforward process occuring in the chloroplasts, the transport and systhesis of the _products_ of photosynthesis certainly takes a certain amount of time.

I'm just guessing, with no science to back it up, that plants evolved to deal with the light cycle nature gave them. They're pretty adaptable, given that we don't kill all of them  , and many people do perfectly fine with a siesta, but lets not oversimplify an organism with thousands and thousands of active chemical processes occuring at any moment.


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## random_alias (Nov 7, 2005)

I'm sorry, I just googled about it and found my original source for that info. It came from Arizona Aquatic Gardens. Their website mentions it and we talked about it over the phone once while discussing variations in lighting intensity during different stages of the photoperiod.

And I won't bother APC with anymore of my posts. Have fun with the hobby!


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## Cavan Allen (Jul 22, 2004)

> With regard to your original question, I must respectfully disagree with Dennis and Cavan that turning the lights off during mid-day will be harmful to the flora, fearing that the plants will have a hard time initiating photosynthesis.


I meant to say that it's hurting by not helping. If that makes any sense...[smilie=p:


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