Okay, so I know a few people (myself included) who are using 20k halides.  I don't think any of us are also adding actinic light.... right???? 
Do all you 20k users think you have enough blue light?  And do you think you have enouh white light?

Adam

I've seen several tanks (including one of my own) that just has 20k halides.  Personally I think it's too blue as it tends to wash everything out.  The corals did fine, but grew much faster when the halides were switch with lower color temp bulbs.

We have silver Aquaspace lights.  There are 2 of them, each 48" long.  Each has 2 x 250 watt 10k d.e. metal halides.  Also included are 2 x 24 watt blue power compacts. 

After watching the lighting demonstration, it seems like his opinion was that the amount of light was not the most important factor, but the distance of the light from your corals.  Did I misunderstand?  Also, the reflector seemed like it was important to the intensity.

Lighting is one of those things that I wonder if we have too little of.  These were $850 each.  I think the cashier thought I was going to pull out a pistol & run away when he told me the total price with tax.  I'm not sure if we have enough light.  Some guy named Adam said, "You can never have too much light." 

Can't wait to see what everyone says!

Travis,

Ding*

Possibly the best question I have read on this forum for months.

Adam

And to answer Travis (JFinch and I have discussed this a lot recently) I would say... well for both.  If my corals don't look good to me, then I want different lights.  If my corals are not close to optimal growth, then I want different lights.

So I'm not really sure I know the answer to that question.

Adam

Adam -

I have a couple VHO's with my 20k's now. One that is a 10k (which is pretty much pink as far as looks go) and a actinic. I think the actinic helps to make up for the totally pink vho. I wasnt getting enough yellow/pink out of my coral, so I added the VHO's. I have been kicking around adding more actinic though - maybe some PC's.

I would say... well for both.

Then the only answer lies within you & your tank.  As a general rule I would say the spectrum that produces the most par would be the most beneficial to the corals... everything else is preference.  Of course if someone has a 400w bulb on a 20g tank that's not going to be an issue because even the lower par spectrum's would most likely be enough for any coral.

I seriously considered the 20k until I found out the par that is lost going from 10k to 20k.  In my tank I think the additional par from a 10k is beneficial.

I'm currently running 2- 10k MH with 2- actinic VHOs.  I wouldn't mind more actinic (I really like the bluer look) but IMO the corals look good and have a nice growth rate. 

So what is the PAR difference between a 150 20k and a 150 10k?  I guess that is a question I should have asked earlier.

Adam

Almost half as much PAR in a 20K bulb compared to 10K. 

But that might not be the whole story.  The 10K bulbs will have more red light then the 20k bulbs.  Can (most) corals actually use the red light?  It's certainly not "natural" to any corals other then some of the sps that sit right at the surface.  This was something I wanted to talk to you about at Dee's the other night... the importance (or unimportance) of red light.

I remember seeing that the par difference on the XM bulbs was something like 250ish PAR for the 20k 150W and 400ish PAR for the 10k 150W.

How far apart are you two halides BTW

Yes, I think you might be simplifying . 

PAR is a measure of the amount of light in the photosynthesis range.  400 nm to 700 nm.  Here is a chart showing photosynthesis rate vs. wavelength for "normal" plants.

Notice the peaks in the blue and red.  And there is essentially no red light after traveling through just a few feet of water.  Everything's shifted to the blue.  Corals have adapted to use blue light.  Do they even have the right photo active pigments to absorb the reds?  I don't know (I'm still researching), but I think it's an interesting topic of discussion.

Back to the bulbs... looking at the spectrums, I'd say even though the 10Ks appear yellowish/white, they still have as much or more blue then the 20Ks.

Couple things- Jon, despite what Mark will tell you (and he'll probably post his pics again) I think red light is MORE important that blue light for corals. 
I think most corals are using blue light because that is all they get, but would do better if they received red light.
Disclaimer- this is something that even the most current journals are still researching.

10k bulbs have as much blue as 20k- big statement by Jon.  Something I sometimes believe, and sometimes don't.  But if it is the case, that makes a huge impact on my decision of what bulbs to use.

My bulbs are about 6 inches apart.  I have two 20k over my 30 gal.  I'm thinking of adding another halide, like a 10k. 

Next question- what are the heat differences between a 150 watt hqi and a 250 watt hqi?  As in the amount of heat they will give to the tank water.

Thanks

Adam

Here is a chart showing photosynthesis rate vs. wavelength for "normal" plants.

I see...  no clue but I understand the question now .  From what "little" I know about it, I think corals could adapt to using the full photosynthesis range.  I posted an article on this a while back but the article was very 'preliminary'. 

Adam have you been able to get your hands on a 10k to see how it would look instead of a 20k bulb?

Interesting idea if you have the room and decide to add a third bulb is maybe having the bulbs placed - l - with a 10k bulb in the center?

Maybe I'll try that.  I haven't had a 10k bulb, but I saw a tank with a 10k on one side, and a 20k on the other.  I'll post pics tonight.
With my canopy and reflector the way it is, I was thinking of mounting them _-_ like that with the 10 in "center".  But I could try -l- instead.  Hmmm, something to think about.  My real question I guess is do I add another halide, or use two pc/vho type of bulbs?

Always changing my lights.... have been for 15 years.... will I ever be happy and stay with something?

Adam

I wonder how much cheaper.  Electronic halide ballast $110, bulb $65 and bracket $20.  That is pricey.  But I don't see VHO being much less.

Adam

You guys need to learn where to shop.

10K URI 24" VHO (with internal reflector)  $20.50 x 2

ARO Electric VHO ballast $35

End caps at homedepot $4

Shipping:$9

Total: $89

These prices are strait off of hellolights.com if you shop around you can probably find better prices.  I really like the cheap endcaps at homedepot, but if you want better ones that will up the price a little bit, but not a ton.

[QUOTE=Travis]Take a look here http://www.advancedaquarist.com/issues/may2004/review11.htm/QUOTE - http://www.advancedaquarist.com/issues/may2004/review11.htm[ /QUOTE ]

You want to know something funny.... that link is to the same issue as my article.  Sanjay and I were printing at that time in preparation for IMAC.  You'd think I would know all the other articles that were published at the same time as mine.... but I don't.

Adam

Here is an interesting link about corals and lighting.  It is translated from german though.

http://216.239.37.104/translate_c?hl=en&ie=UTF-8&oe=UTF-8&langpair=de%7Cen&u=http://www.atiaquaristik.com/2003/0index_meer.htm&prev=/language_tools - http://216.239.37.104/translate_c?hl=en&ie=UTF-8&oe= UTF-8&langpair=de%7Cen&u=http://www.atiaquaristik.co m/2003/0index_meer.htm&prev=/language_tools

Since noone came to my defense  (not even Mark) I'll have to do it myself

Adam, et. al. why do you suppose red light is more important then blue?  I've always thought that red light was just as important, for no other reason then other plants use it, but I've read a few articles that have me rethinking.

For starters here again is the absorbtion peaks for green plants

And here's the absorbance peaks for zooxanthellae:

Notice the difference in the red.  zooxanthellae don't particularly do well with red light.  And there's the potential problem of photosynthesis energy quenching.  Here's a quick and dirty explaination of photosynthesis:

There are two "systems" using in photosynthesis, photo system I (PS I) and photo system II (PS II).  Both systems contain photoactive molecules.  At the heart of both systems is chlorophyll_a with absorbtion of 680 nm (PS II) and 700 nm (PS I).  These are refered to as P680 and P700.  But chlorophyll is not the only pigment used.  There are an array of accessory pigments that can absorb sunlight and then transfer that energy to the P680 or P700 center.  These accessory pigments in zooxanthellae are things such as beta carotene, chlorophyll_c2 and peridinin.  These all absorb light of different wavelength:

chlorophyll_a at 420 nm (violet/blue) and 660 nm (red)
chlorophyll_c2 at 449 nm (blue) and 625 nm (red)
peridinin at 450 nm (blue), 490 nm (blue) and a little into the green
beta carotene at 425 nm, 450 nm and 480 nm (all blues)

Sunlight is absorbed by PS II which throws off an electron and splits a water molecule into O and H.  The O combines with another O and is off gassed as O2.  The electron is tranfered through a series of redox reactions until it finally ends up in the PS I center.  Sunlight is also absorbed by PS I and the electron is moved through another series of redox reactions until it finally ends up powering the calvin cycle making sugar out of CO2.  If any part of this process doesn't work properly then the whole system shuts down.

The pathway between PS II and PS I can be a bottleneck (i.e. the system is at total photosynthising power, saturated... any more energy input into the system will need to be dumped in a non photosythesing maner).  This process is called photosynthesis quenching.  PS II reaction centers can dump this excess energy by two ways.  Chlorohyll fluorescences and the "xanthophyll cycle" where the energy is dissipated as non-radiant heat by conversion of diadinoxanthin to diatoxathin.  That reaction then reverses it's self in the dark releasing heat.  Diadinoxathin is another one of those pigments, but only absorbs blue light.  Other pigments besides chlorphyll can also fluorese to dump excess radiant energy.  Apparently terrestial plants contain a pigment (or some other method) of dissapating excessive red light energy that zooxanthellae don't posses (because they have evolved in an environment without red light).  The way corals regulate this is by reducing the amount of zooxanthellae and/or photopigments, possibly leading to bleaching.

Here are some very good articles:

General explaination of photosynthesis:    http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookPS.html - http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookPS. html

Neat video showing this process (be sure to push the play button):  http://www.cst.cmich.edu/users/baile1re/bio101fall/enzphoto/photoanima.htm - http://www.cst.cmich.edu/users/baile1re/bio101fall/enzphoto/ photoanima.htm #

Photosynthesis in corals (by Sanjay Joshi):  http://www.personal.psu.edu/faculty/s/b/sbj4/aquarium/articles/Photosynthesis.htm - http://www.personal.psu.edu/faculty/s/b/sbj4/aquarium/articl es/Photosynthesis.htm

A few great articles by Dana Riddle talking about red light:
http://www.advancedaquarist.com/issues/nov2003/feature.htm - http://www.advancedaquarist.com/issues/nov2003/feature.htm  (red light bleachs out pocillipora)
http://www.advancedaquarist.com/issues/june2004/feature.htm - http://www.advancedaquarist.com/issues/june2004/feature.htm  (discusses the red light issue towards then end)
http://www.advancedaquarist.com/issues/july2004/feature.htm - http://www.advancedaquarist.com/issues/july2004/feature.htm  (Can you have too much light... ADAM you should read)

Here's a nice quote from the second Riddle article:

If we examine the action spectrum for zooxanthellae, we see that blue and red wavelengths are preferentially absorbed by photopigments. Indeed, we need only to look at absorption of zooxanthellae photopigments. Chlorophyll a absorbs energy most strongly at ~420 nm and ~660 nm, chlorophyll c2 at ~449 nm and ~625 nm and beta-carotene at ~425 nm, ~450 nm and ~480 nm. Specialized forms of chlorophyll located in the reactions centers absorb light at 680 nm, and 700 nm. Peridinin (a carotenoid) absorbs mostly blue light (most strongly at about 450 nm and 490 nm), but extends its absorption range into the green portion of the spectrum. The xanthophyll diatoxanthin also absorbs blue light energy. This is an important consideration, since diatoxanthin is involved in dynamic photoinhibition through its light-activated (and reversible) conversion to diadinoxanthin. As such, zooxanthellae are protected against super-saturating light intensity by the absorption of blue light - if blue light energy is shunted away from photosystems, photosynthesis is regulated to 'safe' levels.

It is important to note that photosynthesis-quenching pigments (such as diatoxanthin) do not absorb red wavelengths - dynamic photoinhibition involves only absorption and dissipation of short-wave radiation such as violet and blue bandwidths. A water column rapidly attenuates red wavelengths (something on the order of 40% in the first meter of the most optically transparent seawater, Jerlov Oceanic Type 1 - 1976) so many corals would not need a specialized pigment to divert red light energy away from photosystem reaction centers. If we disregard the possibility of red-reflective or red-absorbing (fluorescent) pigments acting as photoprotectants, then zooxanthellae/corals do not possess a pigment to protect them from photo-reactive red light energy. It seems the mechanism they possess is a reduction of zooxanthellae and/or photopigment content, possibly leading to total bleaching. Results from recent experiments suggest that degrees of pigment reduction/bleaching are related to red light intensity of artificial light (Riddle - in press).

Evidence does not discredit the notion that red light - at lower intensity - is a factor regulating zooxanthellae pigment content, that is, zooxanthellae might adjust pigment content until equilibrium between PS II and PS I is obtained. If the red light intensity is great enough, photoacclimation may not be possible, and bleaching is a last ditch effort for survival.

Anyway, sorry for the lengthy post, but I hope I'm not the only nerd interested in this sort of thing.

Jon-

Let me start by saying that I read you post like I read most of Marks.... by skimming over it.  I just can't get myself to read posts that long.  Sorry....

Yes I understand photosynthesis.  Looked at the molecules and graphs many times.  I think I may post later, if I can find the enthusiasm, with technical info.  But for now, I'll answer with some very non technical comments.

Jon- 1) if blue light is good, and red light is not, then why do all those stony corals grow in the shallow water, but not the deep. 2) I've taken corals from the ocean, put them in an acrylic tank on shore, and measured the photosynthesis.  They are pumping out energy like crazy in that 6 inches of water.  3) I thought you were the guy who likes the 6500 K bulbs, what's up with all the questions.

Adam

ps- I to was surprised Mark didn't come to your defence

Adam Blundell wrote: if blue light is good, and red light is not, then why do all those stony corals grow in the shallow water, but not the deep.

Intensity.  Intensity.  Intensity.

There is more light 1' under the water then there is 10' under the water.  That includes blue light.  Deep water doesn't increase the amount of blue light.  It just decreases the amount of higher wave lengths of light (i.e. green, yellow, reds, etc.)

In other words corals receive more blue light the higher up they are in the water column.

Yes.

I completely agree with Jake.  I've tried saying that before, but people don't listen to me.  (and they shouldn't, I'm just rambling anyway)
But the difference in blue light isn't nearly as much as the difference in red light. 

Adam

 if blue light is good, and red light is not, then why do all those stony corals grow in the shallow water, but not the deep.

Intensity.  Inensity. Intensity.
Jake's hit the nail right on the head.

Deep water doesn't increase the amount of blue light.  It just decreases the amount of higher wave lengths of light  and But the difference in blue light isn't nearly as much as the difference in red light.

It decrease all light, just red more then blue.  Another great graph from that german site.

Adam, (I posted all that photosynthesis stuff for the benefit of others, I know you know photosynthesis) since you probably didn't read my post and probably didn't read the links (you know there's real virtue in words ) I'll summarize Dana's arguement in a couple sentences.

Zooxanthellae lack the pigments to shed off excessive red light.  Corals compensate for excess red light by reducing the amount of zooxanthellae in their tissue.  As the red is increased the coral can bleach.  Excess blue (to a point) is not a problem as their are accessory pigments that can absorb this light and direct it away from the photosynthesis centers.

I think it would be fairly easy for someone like Dana to prove Adam's point.  Go down 30 m on a reef and measure the intensity both overall and just blue.  Then measure the overall intensity at 1 m.  Take a coral from the reef crest into the lab and supply it with the same blue light intensity as the 30 m depth, but increase the overall intensity to the 1 m depth using red light.  Now see how the coral adapts.

I thought you were the guy who likes the 6500 K bulbs, what's up with all the questions.

I am, was and might still be .  I can see how my last post could be taken as my opinion.  I was just reciting what I've read over the last few months, and it has gotten me rethinking my opinion.  I always reserve the right to change my mind .  Besides, those Iwasaki 6500K bulbs have more blue then the Ushio 10K!!!

I think this is a great discussion...  

My question is, how much red light do the 10k bulbs really have.  Looking at a spectrum chart they seem to be lower in the reds than any other spectrum.

Jon-

I like Dana a lot.  Spoken with him a few times.  Here is an answer to your questions... (notice I said an answer, not the answer)
"Coral growth and color has an intricately woven relationship to lighting..... too bad we don't know what that relationship is."

I really like discussing how corals change color and pigments in different light sources.  I've spent hours at seminars and after class parties talking about this stuff .

The one thing I continue to prove to myself is that I know nothing about this. 

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.
2) A good portion of corals reefs aren't pretty, their junkyards.  (not all coral reefs are pretty)
3) Red light may be more important, or less important.  I don't know, I'm just saying it is far more limiting. 
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?
5) Corals may not be making pigments to look good, but rather to absorb light as a protection (like sunscreen).
6) When it comes right down to it.... none of us know what we are talking about.

Adam

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

"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?

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

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.  

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.

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.

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