Constant or shifting intensity

[Koh23]

So, ongoing debate here, so id like to hear your opinions and how u solve this thing.....

Is it better to have shorter ramp up-ramp down, and fixed intensity for fixed amount of time - example 1 hour ramp up 10 hours constant 1 hour ramp down, OR for that 12 hour period to have ramping up 4 hours, then 3-4-5 hours of full intensity, then 4 hours ramp down?

Probably is the same or very close, average intensity with method 2 is equal(ish) constant intensity full time, which probably is lower than 100%....

So, your toughts?

 

[Nano sapiens]

Corals are quite light adaptable, so either scenario can work out just fine. The DLI (Daily Light Integer) can be similar, but the effects on the coral (especially pigmentation) can be different.

Typical outcome at the extremes with the same DLI:

Short ramp ups/long period of lower intensity: Less intense coral pigmentation

Long ramp ups/shorter period of higher intensity: Greater pigment expression

Of course, too much intensity even over a shorter peak period can be detrimental, so there are limits. Growth can be similar, or not, depending on a variety of factors.

It may seem obvious that 12 hours is best since that's the day's illumination period, but due to the 'angle of incidence' this is not the case (corals underwater only receive around 9-1/2 - 10 hours of light/day). Ramp up is fairly quick, though, so 1-2 hours is more inline compared to 4-5 hours. That being said, experience has shown that 12 hours/day of lighting is tolerated well by corals.

 

[oreo54]

Figure 3. Underwater Photosynthetic Photon Flux Density (PPFD) at a depth of two inches. Hobbyists often call these values PAR (for Photosynthetically Active Radiation).

Light Data from a Hawaiian Tidepool

Can we possibly match the amount of natural light in an aquarium?

reefs.com

 

[Koh23]

So...

Longer ramp up, short full blast, long ramp down, if i'm reading this correctly.....

 

[Waters]

I used to do the longer ramp up time and shorter maximum intensity duration but recently switched to the short ramp up.....growth and color improved dramatically. I think I was starving the coral of light by only giving them my maximum intensity for a short period of time.

 

[oreo54]

So...

Longer ramp up, short full blast, long ramp down, if i'm reading this correctly.....

No depends on what you want to do.
"Naturalists" may prefer that.
Others steady state...short or no ramp to "peak" intensity.


Something worth mentioning as far as I can tell is well before " peak" most corals would have shut down photosynthesis.
Photoinhibition point depends on species as well as how it has been acclimated.

So there seems to be no " better" without considering multiple factors including peak intensity and dli.