# Siesta pros and cons



## lochaber (Jan 23, 2012)

I think the biggest pro is that it works better for some people's schedules. Lets them see the tank before and after school/work/whatever, without having the lights on for 12-16 hours.

I don't think there are any real negatives.

Not sure about the algae thing, and I suspect any reduction in algae was tied to something else, and just happened to coincide with someone using a siesta schedule.

Walstad measured increased levels of CO2 in one of her tanks with a siesta schedule, vs one with the lights on all day. If you are adding CO2, though, this wouldn't really matter.


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## Linwood (Jun 19, 2014)

I'm doing it in one tank, not doing it in another, both low tech. I really can't see a difference in them, plants seem to grow about the same rate, fish seem just as happy in one as the other, no difference in algae (I had some GSA, both getting better with Phosphorous).

I'd love to know if there's some science one way or the other.


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## mattinmd (Aug 16, 2014)

Well, the theory is that during the siesta, the plants no longer have enough light to consume much CO2. During this time, CO2 production from fish/biofilter respiration should slowly increase CO2 levels. 

Walstad's testing of CO2 levels suggests it does, at least in her tank setup...

Of course the stickier question is does it really matter in the general sense? Is the total CO2 available to plants in a 8-on 16 off schedule any different than 4-on, 2-off, 4-on, 14-off? The total non-photosynthetic hours are the same... 

I personally suspect there are some very fine points of biologic respiration rate, amount of aeration, and plant CO2 consumption rate that could make this work in some cases, and not in others.

I use a siesta, but I'm not entirely convinced it works for me as more than a personal schedule convenience (more hours of lights-on when I'm actually home). My tank isn't a Walstad type setup at all, but does have the status of no injected CO2 in common with them.


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## plantbrain (Dec 15, 2003)

Folks that see a difference= CO2 issue(generally, too low), too long of a light schedule , too bright.

Sometimes folks add CO2 poorly, so not enough at the start, then too much at the end, others, simply not enough.

Good CO2, light= 95% of folks problems. Turning them on/off every 1-2 hours was also considered for some that could never fix their CO2 issues. 

Focus on good growth, less on some trick to outwit algae. 

A better focus on cO2 and plant health= less focus on siesta= better plant health overall. Which is the basic goal everyone has.


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## mattinmd (Aug 16, 2014)

plantbrain said:


> A better focus on cO2 and plant health= less focus on siesta= better plant health overall. Which is the basic goal everyone has.


Agreed, but this also assumes you have CO2 injection capability. 

I don't think anyone here who is sane would suggest siesta for CO2 management when doing CO2 injection. You would be much better off just adjusting the CO2 injection rate and timing.

That said, I can see the argument for true low-tech setups (no excel, no injection), where there's no easy knob to turn to increase CO2. I don't buy it, but I can see the argument.


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## roadmaster (Nov 5, 2009)

Me thinks too many people focus on trying to boost growth through increasing light in both low tech and high tech.
CO2 injection makes room for this way of thinking ,but if you can't boost CO2 along with the light ,then reducing the light intensity is the way forward.
Good CO2 levels and distribution seem to me to be assumed in many cases ,and judging from the various problems with algae that folks have even with CO2,, I think getting it right is no easy thing.
Reducing the light is easy, but folks are stuck on their uber lighting which makes getting the CO2 dialed in that much harder.
They sometimes appear to expect four inches of growth each day ,or by week's end.
They want to drive the growth as fast as possible .
Much to be said for low tech ,NON CO2,glut,metricide,excel,etc,if good healthy growth albeit slower and possibly species limited from plant point of view.
These folks learned quickly that it is the light that drives everything, and considering they do not use CO2 or supplement's, they quickly learn that without them,,the light cannot exceed the limit of low to moderate light unless they wish to battle algae rather than watching plant's grow.


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## Linwood (Jun 19, 2014)

mattinmd said:


> Well, the theory is that during the siesta, the plants no longer have enough light to consume much CO2. During this time, CO2 production from fish/biofilter respiration should slowly increase CO2 levels.


When I first read about this, the sense was on light and photosynthesis and not CO2 (i realize they are related). The purported benefit was that plants are better at starting and stopping photosynthesis in dark/light cycles than algae, and that thus alternating light cycles gave a small edge to plants vs algae in efficiency. 

I have no idea if right or wrong, but it was a different sort of argument. Is there any truth to that?

[Google helped] It's also mentioned in passing at the end of the siesta section of this article (at a sight that seems very fact based) as "not demonstrated": 

http://www.skepticalaquarist.com/algae-light-control


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