# Questions on photo period



## tiger15 (15 Mar 2018)

I have been browsing this forum for a while and am impressed by many knowledgeable posters.  I finally registered today and post my first questions on photo period.   I am aware the subject has been discussed many times before but didn't quite answer my specific questions.  

Based on my search, there is a consensus to limit the photo period to 8 hours in CO2 tanks. The explanation is that plants shut down photosynthesis in about 8 hours as evident by some stem plants closing up. So any longer lighting will be wasted or worse, trigger algae.

Question 1: Many aquarium plants are tropical. The average day light hour in the tropic is 12 hour. So in nature, photo period longer than 8 hour is normal, right?

Question 2: Certain stem plants response is not an evidence that all plants respond the same. I keep mostly slow growing Java fern, Anubias, Crypts and Buce and they don't necessarily shut down as stems, but I have no way of telling because they don't open and close up like stems. I have never observed closing and opening of my easy stems: Rotala rotundifolia and Luwigia repens. So why is 8 hour photo period universally accepted as optimum for CO2 tanks?

Question 3: If indeed plants shut down after 8 hours continuous lighting, wouldn't splitting a long photo period into two promotes more growth? Walstad method advocates for a siesta period to allow recovery of CO2 which obviously doesn't apply to CO2 tanks. But wouldn't a siesta period that splits up a long photo period bypass natural shut down and fool the plant into double growth?

I love to be able to increase growth by increasing the lighting period and/or splitting a long lighting period rather than by increasing the light intensity.  Longer lighting period gives me enjoyment of longer viewing time and avoids intense light and thereby less wriggle room for other variables.

I love to hear your opinion or experience on this.


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## foxfish (15 Mar 2018)

Hi and welcome to the forum.
Some folk do indeed use longer lighting periods, 6-8 hours a day is recommend to get beginners on the right track without causing too much algae.
However if you are confident that your tank is under control then you can increase the lighting period a little at a time.
You have to bare in mind though, some folk complain about high maintenance  & super fast growth with only 6-8 hours of light, so perhaps you have not quite got your C02 dialled in too its optimum potential.


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## ian_m (15 Mar 2018)

tiger15 said:


> The average day light hour in the tropic is 12 hour. So in nature, photo period longer than 8 hour is normal, right?


Because in nature the photo period is not full sunlight for 12 hours. It starts in the morning at zero light, maybe max at midday and zero light at sunset. If you have super duper aquarium light fixture that allows timed dimming, you may be able to reproduce this. Most of us have simple on off lights so 8 hours "on average" is probably far more light energy than plants would receive in the real world over 12 hours.

Splitting photo period is one of those aquarium myths that reappears all the time. Plants use energy and take a while to get photo synthesising (maybe upto 3 hours) so two 4hour lighting periods does not necessarily result in better plant health than one 8 hour period. Most people here use just one lighting period and control lighting intensity and lighting period to keep healthy plants and algae free tanks.

Stop "wasting worries" about lighting period and spend more time on getting CO2 levels and distribution right. This is the thing 99% of plant keepers with tank issues are missing, they worry about lighting periods, fertiliser dosing, colour of their filter tubes, my mate does such and such, my tap water contains things, my underwear in yellow etc etc when in fact all along their CO2 implementation is crap.


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## Kezzab (15 Mar 2018)

I have had the wrong underwear issue, don't discount it so readily.


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## Tim Harrison (15 Mar 2018)

Hello Tiger and welcome.

What we aim to do in our aquariums is try and grow healthy plants free from algae by providing optimal conditions, conditions plants won't necessarily get in nature, like Ian mentions above.
6-8hrs of light is sufficient to allow us to do that. But like foxfish mentions many folk use longer photoperiods, it just gets harder to keep them algae free.

Most submerged macrophytes are considered shade plants since they have several adaptations that make them very efficient photosynthesisers at low light levels.
So perhaps more important than light duration is light intensity. Most folk expose their plants to way too much light, and this is where most of the problems start.
The higher the light intensity the more difficult to optimise flow, fertz and CO2 distribution; less wriggle room for mistakes and greater risk of algae.

As you've pointed out different species of plants have different physiological responses to different stimuli. Species such as Anubias and Java fern are adapted to very low light forest conditions and have a very low light compensation point; for instance, they have no need to close up since too much light is never going to be a problem in their natural habitat. They are however, by nature, slow growing and therefore very susceptible to algae; if the light is too intense they soon become covered.

With regards a siesta period, I don't know of any peer reviewed information that suggests this actually works, even in a low-energy non-CO2 tank. However, if a siesta period is more convenient for you in terms of viewing then I doubt it'll hurt. Check this link out https://www.ukaps.org/forum/threads/lighting-photoperiod-rest.51380/#post-504767


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## tiger15 (15 Mar 2018)

ian_m said:


> Splitting photo period is one of those aquarium myths that reappears all the time. Plants use energy and take a while to get photo synthesising (maybe upto 3 hours) so two 4hour lighting periods does not necessarily result in better plant health than one 8 hour period. Most people here use just one lighting period and control lighting intensity and lighting period to keep healthy plants and algae free tanks.
> .


If it takes up to 3 hours to get going with photosynthesis, what’s the benefit of starting co2 1 to 2 hours before light on.  The plants won’t be ready to utilize co2 in full gear right away, so why not synchronize co2 and light on at the same starting time.

I don’t mean two 4 hour lighting period, more like 5 or 6 to give a total of 10 to 12 hour total.  That way it can bypass the natural 8 hour shut down and give plants extra growing time.


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## ian_m (15 Mar 2018)

tiger15 said:


> If it takes up to 3 hours to get going with photosynthesis, what’s the benefit of starting co2 1 to 2 hours before light on. The plants won’t be ready to utilize co2 in full gear right away, so why not synchronize co2 and light on at the same starting time.


The CO2 two hours before lights on is the required time to infuse CO2 to 30ppm level in the water, so that when lights come on the CO2 level is steady. Varying CO2 levels during light period due to poor CO2 management is the start of poor plant health and algae making an appearance.

See here for the maths on CO2 levels vs time. For a typical tank 2 hours on before light appears to be a good start.
https://www.ukaps.org/forum/threads/co2-concentration-versus-time-the-maths.51423/

See Zeus's system for how to achieve 30ppm in much shorter time. (dual injectors bit...).
https://www.ukaps.org/forum/threads/olympus-is-calling.43046/



tiger15 said:


> I don’t mean two 4 hour lighting period, more like 5 or 6 to give a total of 10 to 12 hour total. That way it can bypass the natural 8 hour shut down and give plants extra growing time.


As stated by Tim there is no information that implies this works. If you try let us know.


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## Edvet (15 Mar 2018)

The split period originates from "walstad method" tanks. The idea was the rest period in between functions as a time to let CO2 levels get higher again, so plants benefited from higher levels of CO2 as compared to one period. In reality it hasn't shown to work in measurable ways.
The low energy "walstad" tank will have slow growing plants, no need to force higher growth rates.


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## tiger15 (15 Mar 2018)

Tim Harrison said:


> So perhaps more important than light duration is light intensity. Most folk expose their plants to way too much light, and this is where most of the problems start.
> The higher the light intensity the more difficult to optimise flow, fertz and CO2 distribution; less wriggle room for mistakes and greater risk of algae.
> 
> With regards a siesta period, I don't know of any peer reviewed information that suggests this actually works, even in a low-energy non-CO2 tank



This is exactly why I want to play around with the light duration rather than the light intensity.  I have low to medium light, around 50 par at the substrate, so too high light intensity is never my issue, but then  I am limiting to growing only low light plants.  Even with co2, they still grow too slowly to me.  I am exploring if increasing light duration can induce faster growth without inducing but out pacing algae.  

I read the link on siester period and am aware that there is no proof that siester can reduce algae competition, but what about higher growth rate due to recovery of co2 in non co2 tanks?


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## Zeus. (15 Mar 2018)

Clive (our CO2 Guru) does advise a lower light intensity for the fist 30mins, this is to allow a 'wake up' time for the plants as they are not really ready for full light intensity when the lights first come on so cant photosynthesis at their full potentail thats a little time to reach it. Which is what happens in the real world OFC. so too much light when lights first come on gives algea the edge. Max [CO2] at lights on is important too then stable for rest of photoperiod.

My photoperiod is 6.5hours with peaks and drops thoughtout the period. some lights going up to 60% intensity whilst others only reach 30%. the difference is to match the depth of the leaves varing from just below the surface to 50cm deep with my carpet. it is tricky to get it right and still working on getting mine right and planted it over a year ago


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## Tim Harrison (15 Mar 2018)

tiger15 said:


> I am exploring if increasing light duration can induce faster growth without inducing but out pacing algae


Depends on the plant species, and the plant morphology you hope to achieve, e.g. low compact growth. 
Some species won't thrive on too low an intensity or grow how you'd like them too, no matter how long the duration, although high CO2 conc will help to a degree.


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## zozo (15 Mar 2018)

In discussion like this i just can't help to mention.. If you live in temporate regions with summers that at it's height has 18 hour daylight. Than find a succesfull pond owner with a clean algae free pond.. Take a look at it and ask yourself "How is that possible?" That would be 18 hour daylight at an intensity any invented lamp can not match.. And it works, not for all but it is absolutely possible. 

Indoor in a little invironment we certainly have some ristrictive differences to take into account.. But it aint the photo periode..


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## Edvet (15 Mar 2018)

zozo said:


> ummers that at it's height has 18 hour daylight


yeah but it starts with a few hours overcast and gradually builds up, and all the plants that can't handle that are gone.And look at all the algae products for ponds in the gardencentres


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## tiger15 (15 Mar 2018)

Tim Harrison said:


> Depends on the plant species, and the plant morphology you hope to achieve, e.g. low compact growth.
> Some species won't thrive on too low an intensity or grow how you'd like them too, no matter how long the duration, although high CO2 conc will help to a degree.



I understand photo compensation level below which plants won't grow regardless of light duration.  So substituting longer light duration for lower light intensity doesn't work with plants that don't receive enough light above PCL.

I have low light plants and all receive light above PCLs, as evident by growth notwithstanding slow to very slow.  My tank is 95% algae free except for light bba on the edges of slow growing Anubias and Buce leaves. The faster Java fern and Crypts are fine.  I know increasing light intensity will likely hurt than help, but  wonder if increasing photo period or having long split periods will help or hurt.


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## zozo (15 Mar 2018)

Edvet said:


> yeah but it starts with a few hours overcast and gradually builds up, and all the plants that can't handle that are gone.And look at all the algae products for ponds in the gardencentres


I personaly experience it different.. My tub gets full blast from 9 in the morning with the sun already peaking over the roof till the night fall. And the light at 9 o clock in the morning is brighter than any bulb invented.  I also exprience this with my low tech that stands in door under the skylight. On a day without clouds the tank is brighter lit from the day light at 9 in the morning than from the bulbs hanging above it. Can't even see the bulbs light reflection on the wall anymore and don't see the difference when i switch them off. And thats what i do all summer long, than it's a naturaly daylight lit indoor aqaurium. for the full periode i might add, can't switch off nor dim the sun. And i invite you to come and have a look at the non exploding algae.

And i do not know how many of you guys have been in teh tropics.. But the 12 hour days at the equator ar freaking fast from dawn to full blast and from full blast to dusk. It's minutes.. A bit excaggerated but in my experience compaired it was like POING there is a sun in the morning and PLOP the sun fals in the ocian at night in a blink of an eye.


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## tiger15 (15 Mar 2018)

Edvet said:


> yeah but it starts with a few hours overcast and gradually builds up, and all the plants that can't handle that are gone.And look at all the algae products for ponds in the gardencentres


But pond plants don't get bba, but all other algae.  All other algae don't bother tank plants persistently and can easily be controlled, except for evil BBA.


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## zozo (15 Mar 2018)

tiger15 said:


> But pond plants don't get bba



Indeed never had it in the garden, even throw completely BBA infested indoor plants into the garden tub and they come out clean. Till now the only algae i experiences outdoor is diatomes, aufwugs and Cladophora.. And clado only in the fishless setups.. Goldfish seem to eat it for breakfast. 

BBA likely is an from the LFS introduced tropical algae sp. Can't coop with the lower temps. I dunno.. Best guess..


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## Angus (15 Mar 2018)

ian_m said:


> my underwear in yellow etc etc



When i put on my tighties instead of my boxers it definitely results in some BBA around the edges....


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## Edvet (15 Mar 2018)

All the plants in nature grow where they thrive, if not they disappear.


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## Tim Harrison (15 Mar 2018)

tiger15 said:


> So I wonder if longer photo period or split photo periods will help or hurt.


Give it a go, change one variable at a time; either increase photoperiod or use a siesta period and see if it makes any difference.

I doubt a siesta period will make much difference to growth or algal inhibition, but like I mentioned above, use it if it suits your viewing timetable better.
Extending the photoperiod will probably increase the growth rate of your crypts and ferns, but BBA is a sign of unstable CO2 so your anubias will probably suffer.

You'll probably get better results all round by increasing surface agitation and improving atmospheric gas exchange, at least CO2 conc is more likely to remain stable. https://www.ukaps.org/forum/threads/maxing-co2-in-low-techs.29856/page-3#post-330177


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## zozo (15 Mar 2018)

Edvet said:


> All the plants in nature grow where they thrive, if not they disappear.



I think you hit the nail on the head..  Have thriving plants is the secret.. And not hardheaded persist and try to grow what doesn't thrive.


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## Angus (15 Mar 2018)

Edvet said:


> All the plants in nature grow where they thrive, if not they disappear.


This is how i grow most of my plants if i am honest... survival of the fittest not necessarily the prettiest.


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## tiger15 (15 Mar 2018)

Edvet said:


> All the plants in nature grow where they thrive, if not they disappear.


Make sense, but you can do the same with tank plants.  Walstad suggests planting a bunch of varieties to see what work and toss out the rest.


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## sciencefiction (15 Mar 2018)

tiger15 said:


> I am exploring if increasing light duration can induce faster growth without inducing but out pacing algae.



Even in a low tech tank high intensity and shorter period is superior to plant growth/health compared to lower intensity longer period of light. Playing with light duration is a limited game....


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## tiger15 (17 Mar 2018)

sciencefiction said:


> Even in a low tech tank high intensity and shorter period is superior to plant growth/health compared to lower intensity longer period of light. Playing with light duration is a limited game....



I believe you that majority show class planted tanks get only 6 to 8 hour photo period.  But how do you enjoy your tanks in darkness most of the day or you want to show off to visitors.  Do you turn the light on momentarily and off again after viewing or else risk algae pop up left and right.




Tim Harrison said:


> So perhaps more important than light duration is light intensity. Most folk expose their plants to way too much light, and this is where most of the problems start.
> The higher the light intensity the more difficult to optimise flow, fertz and CO2 distribution; less wriggle room for mistakes and greater risk of algae.



Isn't light requirement plant dependent?  Do you advise against providing too much light above the plants specific photo compensation point? 

Tom Barr has measured Amano display tanks and found the PAR values are surprisingly low, between 35 to 50.  Amano tanks grow only low light moses, anubias and ferns, so there is no need for high light which will likely do more harm than good.

On the other hand, Dutch style tanks grow high light stems with PAR values in 100 and above in order to thrive.  I read that low light plants have hard time coexisting and suffer in Dutch style tanks.


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## sciencefiction (17 Mar 2018)

tiger15 said:


> I believe you that majority show class planted tanks get only 6 to 8 hour photo period. But how do you enjoy your tanks in darkness most of the day or you want to show off to visitors. Do you turn the light on momentarily and off again after viewing or else risk algae pop up left and righ



I set the photo period in the evenings, when I am at home....Generally the earliest mine turn off is at around 9.30-10pm. I have a small tank with an old timer that doesn't hold the time well and it turns on at night, instead of during the day lol. It's planted with only anubias and I still don't have algae issues...it's more about turning on at set hours each day rather than what time that is...


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## PARAGUAY (17 Mar 2018)

zozo said:


> I think you hit the nail on the head..  Have thriving plants is the secret.. And not hardheaded persist and try to grow what doesn't thrive.


And I seen James Findley were he takes us back to his shop setups were a plant has been changed ,often similar of look,because for one reason or another the original plant doesn’t do well, he don’t dwell on it he try’s another plant My photo periods are set for viewing times


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## foxfish (17 Mar 2018)

I have a vivarium that houses many of the same plants as I keep my planted aquarium.
Inside my viv, the plants that you call low light plants like Anubias and moss, seem to thrive on double the amount of watts and twice the photo period.
 You can very often see the quote... low light plants.. but as has been mentioned on this forum perhaps it should read ..low C02 plants.. ?


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## zozo (17 Mar 2018)

There excists something as Photodamage in plants.. The thing for us is, we are growing mainly partialy terrestrial plants submersed. Which is a completely different ballgame of which we probably do not know what from the terrestrial studies still hold true. E.g. in terrestrial invironment and certain plant sp. oftenly heat radiaton is an associated factor with photodamage that doesn't apply to the way we grow the plant. Or as @ceg4048  already explained in many threads that many people mistake leggy growth in aquatic growing plants with etioliaton that could be described as low light photodamage in terrestrial plants. But in aquatic invironment it seems to be a CO² difficiency instead and still the majority blames light intensity when they experience leggy growth.

Funny play of words.. For a great deal, maybe the biggest part it's a shot in the dark  how all these conclusions from studies on terrestrial growing plant/crops relate to growing ornamental plants aquatic. Since this is mainly studied and experienced in a hobby invironment, where each induvidual rather develops an opinion instead of an factual conclusion.


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## Tim Harrison (17 Mar 2018)

tiger15 said:


> I believe you that majority show class planted tanks get only 6 to 8 hour photo period. But how do you enjoy your tanks in darkness most of the day or you want to show off to visitors. Do you turn the light on momentarily and off again after viewing or else risk algae pop up left and right.


I use a programmable LED. The light is on for around 14hrs a day, but outside the 6hr photoperiod it's only on very low light, high enough to enjoy the aquascape but low enough not to induce photosynthesis.



tiger15 said:


> Isn't light requirement plant dependent? Do you advise against providing too much light above the plants specific photo compensation point?
> 
> Tom Barr has measured Amano display tanks and found the PAR values are surprisingly low, between 35 to 50. Amano tanks grow only low light moses, anubias and ferns, so there is no need for high light which will likely do more harm than good.
> 
> On the other hand, Dutch style tanks grow high light stems with PAR values in 100 and above in order to thrive. I read that low light plants have hard time coexisting and suffer in Dutch style tanks.


You have answered your own questions, but to clarify - Aquascaping is just like terrestrial gardening, in the respect that...If you want an easy life, and for your plants to thrive, you will grow them in favourable conditions;
You wouldn't, for instance, try to grow a woodland plant in full sun, and vice-versa, a light loving meadow plant in a woodland. Common sense dictates that you will have your work cut out for you, and in the end you ain't going to be very successful anyway...

However, in our aquariums light is just one component of several that keep plants thriving and algae at bay. Chief amongst the others are CO2 flow and distribution, and fertz regime. Get these right and your plants will thrive and algae will not. Innovations like EI mean we can effectively rule fertz out of the equation and concentrate on the most difficult to pin down - CO2. And as has been mentioned before, ad nauseam, most problems arise from poor CO2 implementation...and further, the higher the light intensity the higher the demand for CO2, and the harder it is to implement effectively.

But that isn't the whole story either. Sure, the key to a thriving planted tank includes all the above, but there is one other factor which is fundamental to success...and that is a healthy and large plant biomass in itself. It creates a negative feedback loop and a biologically stable and self-sustaining system, requiring minimal intervention...which crucially is very resistant to algae. There are several synergistic factors in play by the time a tank matures and reaches biological stability, not least amongst them are probably mutual shading, allelopathy, high O2 conc, low organic content...etc.

And not only but also, as a result it is perfectly possible to grow sciophytes and heliophytes in the same tank, it perhaps just requires a little thought to positioning. Further, on that note plants like Anubias, and ferns are shade tolerant not necessarily "low light plants", there is a not so subtle difference. Take Bolbitis for instance it will grow quite happily in low light but give it relatively high light and CO2 and it will grow very quickly, in fact it becomes a complete thug. Even Anubias and Java fern will put on a growth spurt in higher light, as will many mosses.


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## Zeus. (17 Mar 2018)

@tim, during your extended low intensity photoperiod I take it you have the CO2 off, plus how long of an extended low intensity period do you have just out of curiosity 

Sent from my Moto G (4) using Tapatalk


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## Tim Harrison (17 Mar 2018)

The light comes on at low-intensity 3% at 9am. 
Gas comes on at 11am
Photoperiod starts 2pm
Gas goes off at 6pm
Photoperiod finishes at 8pm
Light stays on at low-intensity 3% until 11pm


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## Zeus. (17 Mar 2018)

Tim Harrison said:


> The light comes on at low-intensity 3%



Thats the beauty of having lights that can go Very low, My Kessil 160 lowest intensity setting is 11% (1.10V on the  0-10V analog input range) which isnt as low as yours can go, spectrum can go as low as 0.0% and lights still come on, where as my LEDs on another tank with aid of a TC420 can go as low as yours


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## Tim Harrison (17 Mar 2018)

Yeah, I noticed that when I was choosing between the Radion FW and the Kessil. It's one of the reasons I didn't go for the Kessil. The Radion can go as low as 1% before zero.


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## Zeus. (17 Mar 2018)

The Kessil 360 have an even higher lower setting which put me off them - think its 30% plus they have a higher output as well. Think you made the right choice in the Radion. That it thats the light/profile of your 'Return of the Shallow' Journal


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## tiger15 (17 Mar 2018)

Tim Harrison said:


> The light comes on at low-intensity 3% at 9am.
> Gas comes on at 11am
> Photoperiod starts 2pm
> Gas goes off at 6pm
> ...


That sounds like an ingenious way to compromise viewing time with photo time.  Just wonder why you provide 3 hour pre CO2 time and 2 hour pro CO2 time, as most people provide 1 hour pre and pro CO2 time.

I am home in the morning and evening so a split viewing and photo time will best fit my life style.  I like to wake up check my tanks and feed my fish the first thing in the morning, and repeat when I get home in the evening.

Here is my current schedule.  I will add dim light to the pre CO2 periods to increase the total viewing time to 11 hour.

6:30 am starts CO2 + dim light
7:30 am starts high light
11:00 am turns off CO2
12:00 noon turns off high light

5:30 pm starts CO2 + dim light
6:30 pm starts high light
10:00 pm turns off CO2
11:00 pm turns off high light

With two short CO2/photo periods, my CO2 peaks at 20 ppm near the end.   I am wondering if it is the reason I still have minor bba on the edges of older anubias and buce leaves, but no other algae.  I have 10x flow turn over rate, light is medium (50 PAR), and all my plants are low light.   Should I dial up the CO2 bps to get more CO2, but then it can lead to more fluctuation in short CO2 periods, or increase the pre CO2 time similar to your set up.


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## Zeus. (17 Mar 2018)

tiger15 said:


> Just wonder why you provide 3 hour pre CO2 time and 2 hour pro CO2 time, as most people provide 1 hour pre and pro CO2 time.



I have 50l tank that takes 3hrs to get a 1.0pH drop whilst my 500L tank I get the same drop in about 45mins. So very tank/injection method dependant. Our CO2 Guru 'Clive' does advise max [C02] at lights on but 4/5 hours later plants have had their fill so for last couple of hours turn it off, which is what I also do and dont get much of a pH increase and lights are dimming by then.

To get a decent full pH drop in an hour is very hard, I get it done with a duel CO2 injection method and a fancy PLC otherwise I dont think its possible to get a stable pH drop in least than a couple of hours IMO


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## zozo (17 Mar 2018)

What you could do is add an extra spotlight above the tank.. At least anywhere in the room in the tanks vicinity with the spot aimed towards the tank.
This spotlight on a seperate timer switch. For example a 3 watt cob led spot or any other intensity depending on the spots/tank distance.

This can give a nice sufficient ambient effect on the tank and room the tank is in. You can choose the best and most appealing position regarding intensity and how it cast schadow.

I'm already doing it like this..




From right to left, Right side is true east. Obviously east is sunrise, that's the first spot that comes on 8 am. It's a 12 watt 700 lumen COB it iluminates 1/3 from the tank and it gets filtered by all the floating vegitation on the surface, it casts a nice shadow towards the left.. Funny is all boraras gather each morning under the floating vegitation for a morning play time. They are attracted to first light. That;s a lovely playfull view..  5 spots every 15 minutes later the next spot commes on, so 9.15 all is switched on. From 8.45 pm the first right spot switches off and every 15 minutes later the next spot switches off 10 pm the last spot. Respectively i have 12,7,5 and 3 watt spot in use. This way i can also play with switching intensity position without the need of reprogramming the controler. It's controlled with the TC420 but i use the JUMP setting not the fade. Each spot comes on at a full 100%. I noticed not all MR16 COB led spot driver like to be PWM faded than it starts to beep. But the spot seperately are low enough so switching 1 on 100% is no shock effect.

The effect is sunrise from the east to west and back down setting from east to west. Also the shadow casting in the tank changes accordingly during this cycle very naturaly. In the morning the shadow in the tank are casted at the left side and in the evening to the right side and mid day straigt down, like a sun clock..

Anyway i realy love it and seeing the 22 schooling boraras following the light play is just an awsome spectacle to look at.. Tho i'm to only one noticing this minor detail.

But if you have a fixed light source adding 1 extra spot light for the ambient evening light. clamped to the tank or screwed to the wall what ever can give you a lot of fun.. Make it 2 spots and you can have a sun up and sun down/moonlight effect as well.

I'm actualy planning a change for this setup.. I'm thinking of fixing a goose neck on the far right and far left spot, to be able to play more with light angle.


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## sparkyweasel (17 Mar 2018)

That's what we did in the past, without modern controllers, a dim light coming on before the main light and going off after.


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## Tim Harrison (18 Mar 2018)

tiger15 said:


> Just wonder why you provide 3 hour pre CO2 time and 2 hour pro CO2 time, as most people provide 1 hour pre and pro CO2 time.


Take a look at this thread https://www.ukaps.org/forum/threads/co2-2-hours-before-lights-turns-on-why.51367/


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## tiger15 (20 Mar 2018)

All the info I received are great including links to more info. 

I am fully convinced that high intensity light and short photo period not exceeding 8 hours is best for the plants.  There is no demonstrable benefit of a siesta period and it may even confuse plants giving an edge to algae.

That said, I will stay with twin photo periods from 7:30 -12:00 am and 6:30 -11:00 pm daily which best fit my life style for viewing.  The gap is not a typical short siesta but more like a long 6.5 hour resting period not significantly different from the night time 8.5 hour resting period.  It's like I spin the earth twice as fast to short change the plant day to 12 hour and provide 4.5 hour photo period daily.  From the input I received, plants get their fill in the first 4 critical hours, but may need 1/2 hour to get going. 

With short photo period each plant day, I have dialed up the CO2 to attain 30 ppm earlier.  I turned on CO2 and dim light 1 hour before and off CO2 1 hour earlier in each photo period.  

 I know nurseries manipulate photo periods in green houses to fool plants into blooming or accelerate growth. I don't know how aquatic plants will react to shorter plant day cycle.


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