I've spent too much time talking to Jake about coral lighting and pigments.  I think I can safely say "I agree with Jake" on all of his comments (except for #3 above, what is up with the no comment?). 

I've even spoken with Jake about his crazy idea to grow flourescent green zooxanthellae and inject them to make green xenia. Or grow blue and inject them in claudiella to make a nice super blue colt coral. 
(scary part is that Jake may know what he is talking about, and this may be the future of coral farming)

Adam

Mark Peterson wrote: Jared wrote: End caps at Home Depot $4 Where? I gotta see these BTW, $27 is a special WMAS members price for a 4'

They're just the standard endcaps they had in the lighting secion of homedepot.  Nothing specail, they were identical to the endcaps on my AGA NO light strip.

Adam said:

Some food for thought:
1) All those lights that make your corals glow and look pretty... are lights that aren't helping your corals grow.

True...corals have nice colors because they are blocking out light they don't like.

2) A good portion of corals reefs aren't pretty, their junkyards.  (not all coral reefs are pretty)

Adam, all reefs are pretty.  Even the brown corals growing on the rusted sewer outlets.

3) Red light may be more important, or less important.  I don't know, I'm just saying it is far more limiting. 

No comment.

4) I have a very difficult time believing we will over light our corals and bleach them.  Isn't it amazing to walk up to a reef at low tide and see miles and miles of acropora and montipora sticking out in the air?

IMO corals don't bleach because of too much light, but bleach because of too much light too quick, or too much light of the wrong spectrum.

5) Corals may not be making pigments to look good, but rather to absorb light as a protection (like sunscreen).

True, as I mentioned above.

6) When it comes right down to it.... none of us know what we are talking about.

True also.  This is all just speculation.

has anybody actually measured the light at different depths out on the reefs

Yes, but every reef is different.  It's a function of turbidity in the water.  Reefs near large land masses tend to be in more turbid water while barrier reefs out away from land can have very clear water.  There's charts in a Steve Tyree book that shows light transmission through a couple different "types" of ocean water.  I've seen similar graphs elsewhere.

Thanks for that 1.67 calculation Jon

Hey, I'm an engineer it's in my blood.  

Mark- go halide, you can't have too much light. (plus a few of us can't wait to see you with halides)

Jon- "So are you of the opinion that over illuminating problems are all acclimation related?"  I don't know.  Sometimes people say "I bought this green coral, put it in my tank and now it is brown".... to which I think "maybe you bought a brown coral and now it is finally happy that it doesn't have to be green". 
That probably isn't the case, but I don't know. People can talk lumens and par all they want, but to me... we never over power our tanks.  Yes I admit, so corals like mushrooms (although not corals) do better in low light, but in general, I don't think we are overpowering our corals. 

Thanks for that 1.67 calculation Jon.  Not exactly what I was looking for, or maybe it was??? Hmmm, I was actually waiting to hear someone say "not much more" or "a lot more".

No I'm not going to start keeping SPS!

Adam

"Coral growth and color has an intricately woven relationship to lighting..... too bad we don't know what that relationship is."

*ding*

Are my 20k XM halides giving off enough actinic (blue) light, that I don't need to add more?

I don't know, but I'm currently of the opinion that intensity is, as important, maybe a little more, then spectrum.  That is why I prefer 10K (give or take a few K) bulbs.

How much heat does a 250 watt bulb give off, compared to a 150 watt?

That I can qualitatively answer... 250/150 = 1.67.  So, I'd say they will generate 67% more heat.

I have a very difficult time believing we will over light our corals and bleach them.  Isn't it amazing to walk up to a reef at low tide and see miles and miles of acropora and montipora sticking out in the air?

huhhh... are you going to start keeping SPS now 

So are you of the opinion that over illuminating problems are all acclimation related?

Sorry, I forgot what this topic was about... I just went back to see... and low and behold I started this topic.

So back to my original questions-
1) Are my 20k XM halides giving off enough actinic (blue) light, that I don't need to add more?
2) How much heat does a 250 watt bulb give off, compared to a 150 watt?  In other words when I added my two 150 watt bulbs my tank temp didn't rise (at least I don't think it did) but what would happen if I used 250 watt bulbs?

Adam