Adjustable LED's and SPS Corals

[edsreef]

I'm in the process of gradually ramping up the PAR on my new LED lighting in my newest tank. In the years past I've used both Iwasaki 6500K and XM20K 250W metal halide lighting supplemented with URI Super Actinic VHO's.

I always got the best/fastest growth with the Iwasaki 6500K's and the best coloration with the XM20K's.

I've played with different settings with my new adjustable Cree LED lighting and can have anywhere from (what I consider) powerful 10K crisp white/blue lighting to a slightly more subdued 20K blue look.

Since I'm starting out with small frags I'm wondering if my initial goal should be to work up to a powerful 10K type setting for best growth or the 20K type setting for best coloration. If I do this, will I be able to change back to the 20K setting and see better colors out of my corals or will they remain slightly more drab?

For those of you with adjustable LED lighting, how have you handled this dilemna?

 

[aqua80]

I always got the best/fastest growth with the Iwasaki 6500K's and the best coloration with the XM20K's.

not sure you can think like that with adjustable leds...
with a 250w 6500k MH vs 250w 20000k MH, the latter will produce less PAR
(a least I think...) therfore less growth...

with your led setup, the best growth one acclimatation is done will be with all your leds availaible on at 100% (greatest PAR). If you dim the Blue leds to have a 10k "look", you will have less PAR avalaible for your coral and less total watts output (and blue leds are the most efficient in terms of PAR).

that's how I see it !

 

[hk855]

I am building an led fixture for my tank and am deciding between 2:1 or 3:1 blue:white ratio to solve this high par good color debate. Like aqua80 said at 100% is going to be your best growth irregardless of the appearance. Also the blue spectrum is high in par, red is too but not quite as much. Your typical 6-10k bulb has more par because it's designed to produce the red spectrum and you get more red photons than blue per watt and hence more par. So for growth max them out, if you want better color drop your whites some. Getting your color to change is possible but will take a while, requires better water quality and isn't guaranteed especially in the older growth.