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Discussion Starter · #1 ·
I have been using the siesta lighting approach for years. It makes sense to help the plants out-compete the algae, as well as keeping the lights on during the two periods when people are around the tank (morning / evening)

It's also trivial to implement with any fixture and a simple timer.

However, we now have access to much finer control over both brightness and spectra. e.g. the AI Prime Freshwater

Lamps like that allow a "natural" increase in intensity over a day, and even a way to change the spectrum during the daily cycle.

Of course, one can implement a siesta with such a light.

Question: In our tanks, is the hard Light/Dark/Light true siesta the best way to help in the plants vs algae competition? Or, will a gradual ramp up then down do the same?

Secondary: One could do two peaks per day, or maybe do a selective siesta where some wavelengths are taken out for the "dark" period.

Thoughts? Science? Speculations?
 

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You mentioned science. That means certain steps the way I see it:
a) theory (assumption)
b) experiment
c) proof
d) law (or at least a conclusion)

What you suggest sounds reasonable. I am curious to what results you come to!
 

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Discussion Starter · #3 ·
Right - I can do an experiment, though I'm not equipped to do a very carefully controlled one.

Those who know the biochemistry well may be able to predict the outcome...
 

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The siesta method is discussed a lot in the “el natural” forum.

Diana Walstad explains in her book (with data and research to back it up) that siesta periods are good for tanks due to the fluctuations of co2 and o2 in the tank.

A quick overview is basically the plants use up the available co2 by about midday. With the siesta, it allows it to rebuild and then there’s enough to use once again in the second half of the day.

This also inhibits algae growth by giving the plants what they need to grow and outcompete the algae. The general siesta period is about 3-4 hours.

Also this is geared towards tanks without co2 injection.
 

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I've thought the same thing as the original poster so I recently changed from a beamworks FSLED and 3 1/2 siesta to a Finnex planted 24/7 running its standard day simulation cycle. I have a 75 gallon aquarium and the new lighting change has been going for about 2 weeks. So far no algae problem my dwarf aquarium Lilly has a surface leaf. It has not reached the surface since I planted it 5 months ago. Also my ocelot sword has two larger and more vibrant leaves. I'll try to post some pictures Monday.
 

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Discussion Starter · #6 ·
I got out my well-thumbed copy of Ms. Walstad's book (and found the addendum to the lighting section, p.178) she put out in 2018. You can find that here:

No new realization from the re-read, just the confirmation that it's light & low levels of CO2 that benefit algae over plants. It doesn't discuss low-light, but most of us know from experience that too little light leads to much algae.

I now have three of the AI Prime Freshwater lights over a 100g, 60".

  • Set with a 1 hour ramp up and down on either side of the two lighting periods, with a 3.5 hour siesta between them.
  • The morning max intensity is 2 hr long, the afternoon one is 3.
  • The highest intensity (warm light = cool light = 50%) is set just below the point where the lamps' cooling fans turn on. (Wish that PAR meter was still available for rent.)
  • Not using moonlight for overnight glow
  • About 30 days with the new lights now
  • No dosing in this tank, just fish food

Observations so far:
  • I really like the gradual increase and decrease in light. That, plus the more focused beams than the five CFLs I had before make for more dramatic lighting and interesting variation during the day.
  • There is some green fuzz algae growing on the substrate
  • The CO2 indicator (new liquid) shows no variation during the day that I can tell. I may need to get a more accurate test method.

Open question is still:
* Is the lower light intensity during the ramp up / down a disadvantage to the plants?

Would be cool if someday there was a CO2 "thermostat" which could adjust the LED brightness based on available CO2 to optimize growth when one's not at home. Hmm.
 

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In nature, water is usually illuminaged in morning and evening more than noon so I would assume like a siesta would work out, I have mine so in the morning it gets sun and in the afternoon I light it.
 

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Τhe gradual increase and decrease in light sound great, I am sure your fish probably appreciate it as well! No surprises etc ;)

Regarding the CO2 "thermostat", perhaps it could be done with an automated ph meter that measures ph in programmed intervals, provided that you enter the kH value in advance. If kH is stable between water changes, then ph is the only variable that I can think of which would affect CO2 concentration. I do not know how easy it would be to accomplish something like this, but a quick web search on kH fluctuation* led to me this product:


With the output of a measuring device like this (both pH and light meter), perhaps you could adjust your light intensity throughout the day accordingly, even while not at home. But I guess you'd prefer it fully automatic, so that would dictate the need (wish?) of a device/application that would make these work together.

In case you find something that does such a thing, I'd be really interested to know!


*tried so see if my assumption of kH being stable between water changes is reasonable. Or at least if it changes a lot slower than ph...
 
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