Weekly Debate

[Debater]

Hey Reefsters,
We are going to try something new. Every week we will post a debate that will run for a week. Once the week is over the debate will become unstickied and a new debate will be posted. This new idea is drawn up as a debate, so don't treat it as a newbie that is trying to get information. State your opinion and, if available, use material that will back up your opinion.

This week's debate:

Radium 20K bulbs are becoming very popular. Have they proven themselves or is this some directionless fad? Have they been around long enough to show real promise about their long term effects or are people just buying them because their short term effect looks grand? What is your opinion?

 

[npaden]

LOL,

Well, I'll be the first to chime in with my 2 cents!

I think they are a fad. When it comes down to it the corals need PAR. The color of the light in question is far more for the individual who is viewing the coral than the color itself. I have seen excellent growth and coloration under my plain old Iwasakis and some of the best coral farms are now using extensive natural sunlight and have excellent results in both coloration and growth.

As far as scientific information backing up either side I think there is very limited real information. It's all speculation and anectodal.

I'm sticking with my 400W Iwasakis. Still the best light under 1,000W IMO.

Nathan

 

[danmhippo]

20K? I think you meant 20,000K?

 

[Debater]

Of course 20,000k. 20k is used liberally for 20,000K. Its the sign of laziness for typing that extra K or the extra zeros.

 

[ReefMon]

I think he's saying they are WAY to blue to provide the proper amount of useable light for high light corals.

IE: 200,000K

Let the fight begin! :lol:

 

[Debater]

I am not saying anything. We want to hear your opinion. I am just the debate poster with no opinion.

 

[Bill2]

Lol interesting name debater... are you a master at it?

Sorry had to say it

 

[jamesw]

I have found that most beginning reefers really want a BLUE looking tank with flourescing corals. The radiums give you that.

They probably work fine if all you are keeping is LPS and soft corals - which is hopefully what most beginners have - but I don't think radiums are too good for acros.

Now that I dive a lot I see what the reef really looks like. Even deep - it's not "blue" looking - it's more like the other colors are missing. In shallow water - the reef looks a lot like my tank w/ an iwasaki - so I like it. Plus, the 6500k lamps are the most powerful.

So I wouldn't switch to radiums - probably even if someone gave me one to try.

Cheers
James Wiseman

 

[danmhippo]

No scientific proof for backup, but I observe faster growth of my softies and polyps under 6500K switched from 20,000K.

I have to say that I didn't liked the yellowish look of the 6500K versus 20K-K. But after observing coral polyps' responses to it after several weeks, I will not go back to 20K-K anymore. I will stay with the 6500K or 10K-K bulbs.

BTW, the seahorse avatar, the shot was taken under 6500K. That paticular SH looks more mottled yellow when being kept under 20K-K lamp.

 

[liquid]

For reference purposes for this debate, let's look at our library:

Steve Tyree promotes the higher color temperature lamps in his talk on #reefs back in June 2002: http://www.reefs.org/library/talklog/s_ ... 60202.html

After reading that does it change your mind about higher kelvin light sources?

Shane

 

[Bill2]

When seeing the wavelength plot from Sanjay the Radiums did have a pretty good PAR value. They did have most of their intensity in the blue value.

The one thing Radiums do have going for them is their largest spike in wavelength is where chloraphyll has almost 100% absorbtion. (do i have that right?)

Bill

 

[JT]

but I don't think radiums are too good for acros.

However, there are quite a few people such as Steve Tyree and Dr. Mac who have been growing SPS corals under Radium lamps for quite awhile with a great success rate.

- JT

 

[reefland]

However, there are quite a few people such as Steve Tyree and Dr. Mac who have been growing SPS corals under Radium lamps for quite awhile with a great success rate.

I was going to make the same point.

A question like this also needs to be specific enough to include a ballast.

There is visual difference in how the bulb burns on a HQI ballast, BlueLine or regular PFO type ballast. If your eye can pick up the difference then I'm sure the corals will notice a difference as well.

 

[wnfaknd]

Dr. Mac uses 400w Radiums for his acros and he swears by them. Most of you know that his corals are pretty awesome. Then again, he keeps the corals just a few inches away from the light bulb...

 

[npaden]

Okay,

So one argument is that the blue spectrum is the best spectrum for a specific species of zoox to photosythesis at. The idea is that we should saturate that spectrum while excluding light in the other spectrums. I personally like the use of a full spectrum bulb that will benefit a wider variety of inhabitants in my tank. Light that may grow some micro algae that my amphipods may then eat then they might reproduce and feed my coral.

As far as the whole coloration issue of an individual coral I still think there are so many factors to determine a particular coloration of a coral that a specific light bulb can not account for a specific coloration of an individual coral. I have frags from the same coral growing in different areas in my tank under basically the same intensity lighting and they definetly have different colorations.

In this chart of lighting intensity at certain wavelengths (taken from Sanjay Joshi's website) it shows that at the particular wavelength that Tyree says is ideal for the one strain of zoox in his study the 20KK radium does show to have a little over 20% more intensity than the Iwaski bulb. But in the violet, green and yellow spectrum the Iwasaki blows the radium away. The radium may be better for a specific zoox in a specific coral, but it doesn't look to be better for you entire tank IMO.

If you read Tyree's article closely, he actually recommends a blend of lighting choices to get a full spectrum of light but he wants it to be heavy on the blue spectrum. I think the Iwasaki bulb provides the closest thing to a full spectrum by itself, and radiums if used exclusively may not meet the needs of all of the inhabitants in your tank.

Oh well, just adding some random thoughts.

FWIW, Nathan

 

[Bill2]

I personally find the 20k's too blue but that's a preference thing. I think at this point the anecdotal evidence seems to show that 20k's are doing pretty well. We'll see once some of these bulbs get to be a year old

 

[Mouse]

Wehey, Mass-debate.

 

[Anonymous]

Dr. Mac uses 400w Radiums for his acros and he swears by them. Most of you know that his corals are pretty awesome. Then again, he keeps the corals just a few inches away from the light bulb...

Yes, they do look pretty amazing. Would anyone know or care to guess how long he keeps them as such (in his possession, in his systems)? Not very long I'd wager except the captive fragments and those aren't anything special IMO. It's the wild colonies that are the spectacles and judging from how often his site is updated, he doesn't have them very long at all. Therefore, I see Dr. Mac as no argument whatsoever for the long-term results of 20K usage (nothing against him you know).

 

[monkeyboy]

I'm in it for the par, not the color. IMO, you shouldn't need a fancy light bulb to make your corals have nice color, they should have it themselves w/out extraneous useage of bluer lamps. I have a pink acro under 400w 6500k's with 2 vho actinics, the color of the tank is just about white, and it flouresces like nobodys business. I like the idea of supplimenting 6500k's w/ radiums to boost the color to white and increase the par significantly, otherwise i wouldn't use them alone.

I suppose if you have a tank full of brown coral, added blue will make some floresce green or bring out subdued color a bit, but it's not the lamp that's the problem.

If you like blue, hang out for your dawn/dusk w/ actinics, it does look cool. But i guess it all boils down to personal preference, and what big mama nature has to say about it.

 

[jamesw]

What Graham said. The corals and coral frags that Dr Mac gets from Fiji are truly spectacular, but I don't think the locals in fiji use 20kK lamps...I think they use the sun...

Cheers
James