Question about LED intensity and exposure time

[b4tn]

When it comes to intensity and coral health is 2 hours of fully intense light equal to say 4 hours of light that is only 50% as intense?

I am trying to work out a ramping schedule and I am not sure if I should shrink my full intensity time since it takes the lights 3 hours total to ramp up and down

 

[Mathieu Lafleur]

When it comes to intensity and coral health is 2 hours of fully intense light equal to say 4 hours of light that is only 50% as intense?

I am trying to work out a ramping schedule and I am not sure if I should shrink my full intensity time since it takes the lights 3 hours total to ramp up and down

What's you LED fixture?

 

[b4tn]

What's you LED fixture?

Its an ORt247, so I am only ramping blues and whites. My current schedule is 10 hours of blue and 8 hours of white. 65/45

 

[oreo54]

https://en.m.wikipedia.org/wiki/Daily_light_integral


Theoretically yes.
10 hours of 50% is equal to 5 hours of 100%

 

[jda]

Yes, it is true in theory. This assumes that you do not oversaturate when you are at the higher level - this is easy to do with some diodes. Be careful... LED are somewhat unique in that they can burn/kill coral when up too high. This is likely a quality thing since the same, or more, PPFD (PAR) from a T5 or MH would not burn or kill coral.

In application, this seems to be more in play with longer exposure times at lower intensity. Of course, it makes no sense to run 1000% for 1 hour instead of 100% for 10. People use this principal to have nice reefs with less light by leaving the lights running for 12 hours, or so.

 

[b4tn]

Everything seems happy at my current schedule of 65 blue from 10-8 and 45 whites 11-7 I get both SPS and LPS growth, lots of coraline, and can manage algae. The ramping is purely aesthetic for my vieing pleasure so I am trying to keep the lighting close to the same. This is what I have come up with

Blue starts at 10am at 10% ramps to 65% by 11:30 Ramp down starts at 19:30 to 10% by 2100.

White Starts at 11am at 10% ramps to 45% by 12:30 Ramp down starts at 18:30 to 10% by 20:00

 

[Dana Riddle]

I'm not trying to avoid your question but if your corals are doing well I wouldn't change a thing. Do you have any PAR numbers to share?

 

[b4tn]

I'm not trying to avoid your question but if your corals are doing well I wouldn't change a thing. Do you have any PAR numbers to share?

Like I said purely aesthetic. I like the way ramping lights look. I do see what you are saying, I could leave well enough alone, but I know many use a ramping schedule successfully and now I have the means to do it myself.

 

[oreo54]

So basically you are going from a 10 hours of "full" light (65%) for blue to 8
8 hours of full light for white (45%) to 6

The 2 full hours are replaced by 3 ramp hours..

There is simple math ways to approach this but believe the simplist is area..
Looks to be your new system is 25% less bright than an equiv 2 hours of full..

Extending your ramp to 2 hours each "should" equalize it ..

NOW
THAT said this hasn't been my best period of calculating things..

OK couple more things:
Using a "PAR" meter and any number of the DLI calculators available will also work
http://support.specmeters.com/kb/qu...ght+Integral+(DLI)+with+a+Quantum+Light+Meter
One assumption is that you are using PWM dimming and the dim "curve" is linear..

Got to cover all my bases here..

 

[oreo54]

Note area lost vs area gained..
Blue line is 2 hour ramp..

 

[b4tn]

Awesome, thats a great way of looking at it.

Thanks

 

[dantimdad]

I'm not trying to avoid your question but if your corals are doing well I wouldn't change a thing. Do you have any PAR numbers to share?

Go with Dana on this one!

If it ain't broke...