Bleaching from lights. Must intensity change or can timing?

[speedstar]

I am suspecting some bleaching due to DIY LEDs must i change the intensity of the light or can the lights on duration just be shortened? These are 3w Cree's but under driving them, running 55 of them mixed values with 90 degree optics. Over a 36inch round tank. Basically just needing to cover a 2x2 area with SPS. It is very shallow meant as a look down tank so I suspect the PAR is very high at the Corals.

You can see hopefully in this pic how the top side of the cap is bleached but the lower front slope is not.

Opinions please.

 

[Amphiprion]

It is more preferable to reduce intensity, since photosynthesis is not time limited, but rate limited. In other words, it is limited by how much light enters the system only, not how long it is entering. I typically do a bit of both, but focus on intensity. If you didn't limit the intensity and only shortened photoperiod, it would be akin to holding a hot pan for a shorter amount of time--it would be better to let it cool off a bit first.

 

[sponger0]

But you also didnt say how long you were running your lights too

 

[speedstar]

But you also didnt say how long you were running your lights too

Nine hours.....

 

[sponger0]

Then I would say the intensity of the lights.

 

[kevensquint]

Pop off the optics. You should then have around 120° spread....less intense, more homogenious spectrum.