I believe it's a matter of a number of different things. Your tank is much more broken in than mine, I assume you'll see more stable conditions that I will for a period of time so I would expect you to see better growth if we were to use the same light. Your method of dosing will be different from mine, I'm using a few different things while I slowly add to my Tim Taylor/RedGreen collection of Dosing systems, IE my Kalk Reactor, Ca Reactor that I'm working on etc. The Salt you use probably makes a difference too.
All in all... I wish I had half the answers...

Doug

I have seen some tanks with 250 watt low Kelvin bulbs and they simply blow away tanks using higher wattages in terms of coral color. There is a lot more to color and growth than lighting, e.g. alkalinity, water movement, DOC etc..

Re: Effect of wattage on coral colour...
 

well if you would have been at the meeting you would know :wink:

seriously though, it is being found that you can achieve phenominal growth (but not good color) with NO lights, as long as you have some sort of event to triger the photosysnthis. this can be an event such as a camera flash, or a higher bulb comming on for a few miniuts then going off.

learned a lot of cool stuff, some new and different ideas but cool none the less. this theory would explaine why I am getting the same growth rate on my corals as I did with my PC's and the 175W bulbs as I do with the dual HQI's.. although color left nothing to be desired back then.

Steve

I snipped this from a thread on RC because I thought it really explained everything about coral color...reprinted without permission, but hoping nobody minds...

"there are only two things which affect sps coloration. These are zooxanthellae density and accessory pigments.
Accessory pigments are determined by growth, light intensity and spectrum.
growth is also determined by calcium availability, alkalinity, trace elements, flow, temperature, salinity, food and stability. zooxanthellae density is relative to nutrients, growth, temperature and light intensity, spectrum and duration.

when corals exhibit fast growth, the growing margin has fewer zooxanthellae and more accessory pigments leading to colorful tips or rims.
Zooxanthellae can mask colorful pigments when they are in high densities. In nutrient poor conditions and under high light intensity and ideal spectrum, zooxanthellae populations will be further reduced leading to more visible accessory pigments especially within the body of the colony.

As you can see already it is a very complicated and weakly understood process and I am sure I have left something out.


__________________
Jake Adams"

Steve, that doesn't explain then why I experienced greater growth with bigger lights....

Steve, that's interesting. So there is a chance that if I go to two 250w MH rather than going to a two 400w MH I can see similar growth but possibly not as good colour out of SPS?

Brad, that sure makes sense.

Doug

Doug, what is "good colour"? Some corals may respond better to 250w than 400w, depending on your answer to the first question....

I knew that.. I just forgot it. That would explain also why I'm not seeing much grown on a couple of my frags from the last meeting but the Pink Birds nest has lots of little nodes popping out all over it.

Doug

We have to remember, of course, that we cannot truly establish causation without parallel environments with only one manipulated variable. It may not be the change in lights affecting growth or coloration. Of course anecdotal evidence is about the best we can get in this hobby in the course of a discussion that takes us a day to wrap up, and I will settle for it. :mrgreen:

Quinn I gotta learn that language you speak...lol