Metal Halide Bulbs/Spectrum

[Beckmola24]

What is the difference between the Metal Hailde bulbs?? 5500K, 6500K, 10000K, 12000K, 13000K, 14000K and 20000K? This is a lot of numbers, but I am unaware of what each spectrum will provide for corals. What are common ones to use over tanks? What would be a good spectrum variety for a 90 gallon tank 24" deep? I have a unit that is 48" long. I already have 2 T-5 actinic bulbs, so I'm good in that category. I also have HQI double ended sockets. I was told the HQI's were the way to go, but am unaware exactly why. Thanks in advance!

 

[reedman]

Hey Becky,

First, this is a very contraversial topic, so I will provide my opinion as just that...my opinion.

As the numbers get larger they shift in spectrum from 5500 having a spike in the green/red area (I think) to 20K which has a large spike in the blue/violet area. There are a few different ways to discuss this. From a visually apealing point of view I like the 10K and 20K bulbs. 10K usually has a nice crisp white color to them and 20K has a slight to major blue tint to them.

Some people are growing corals to grow them, not to look great...and for this most use the iwasaki 6500s. They have a very strong PAR number and penetrate the water farther. They are more on the yellow side, so actinic suplementation is recommended.

12K, 13K, & 14K are typically variants of the 10K and 20K. I will try to find the spectral plots that Steve Tyree used to explain this. They were very informative in matching what the corals use and what the bulbs put out. He recommends mixing bulbs on larger tanks (3 or more bulbs on a tank), as no one bulb provides the "correct" spectrum for a coral. Barring this ability (which many of us don't have) he recommends finding a bulb that meets a large portion of the corals useful spectrum and then going with what is visually appealling.

My recommendation is to look at several people's tanks in person and see what you like. In the NW there are a lot of people with MH on their tanks and most of the spectrums are represented. I'll try to post some links later if no one beats me to it.

-Reed

 

[Beckmola24]

I know that the longer the wavelength of color the shorter the frequency, so you would lose colors on a reef in corresponding order; red, orange, yellow, green, blue, indigo, and violet. Blues and purples penetrate the water the deepest because of their higher frequency. So what I'm asking now is what color spectrum matches up to the Kelvin number on the bulbs? If possible I would like to have a happy medium. I would like to grow corals, in moderation, and have them look nice.

 

[reedman]

I would say the 10Ks are the closest to what you are describing.

 

[Ed Hahn]

Becky,
HQIs produce more light and are easier on your pocket due to electronic ballast. They also burn more even due to double ended bulb. I think you did great getting HQIs. Do you have a two bulb HQI System? A lot of people I know are using a 10k and 20k bulb combination. I have been using the 14k and 15k bulbs. I have been able to grow about everything so far...knock on wood.
My two cents, I hope it helps
Ed

 

[Beckmola24]

I have a 48" halide unit with 2-250 Watt HQI bulbs and 2 Actinic T-5 bulbs. I went ahead and got 2 10,000K bulbs, but I wanted to make sure this was ok. I could trade one of them for a 20,000K if need be. Will that be enough lighting for a 90 gallon tank that is 24" deep? I can always add another socket and bulb to the middle of the unit. Should I trade my 10 for a 20,000K bulb??

 

[Katchupoy]

I think that is one mean lighting setup... Good for you Becky....

 

[CarlaW]

Becky,
I ran a 250w 10k, and a 250w 20k on my 80 for 2 weeks and it bout drove me crazy. The difference between the 2 was amazing. I ended up with 2 20k's. I really like the blue I guess.
The growth rates of my corals didn't seem to differ much either. Like Reed said, go visit a bunch of people with the different bulbs. It really helps you decide which ones you want. HTH

 

[WaterDogs]

Just my two cents I had 20k MH and I didn't like the look at all, nothing but blue. I have 10k now but will consider 12 or 14, but not 20s.

 

[Ritsuko Nashida]

I am using 10K's right now with actinic VHOs and it looks pretty good, white with a slight hint of blue. But to be honest with you...I am thinking about going with 12-14K bulbs though so I can get a touch more blue tint to the light. Like WaterDogs I cant see doing 20K's as they are way too blue for my taste.

 

[Ed Hahn]

Becky,
Look what I found. I hope this helps. http://www.coralreefecosystems.com/ltg_bulb_color.htm

Ed

 

[Scooterman]

Thought I'd post a few good links.
Enjoy;

http://www.advancedaquarist.com/issues/oct2002/feature.htm

http://www.aquabotanic.com/lightcompare.htm

http://66.102.7.104/search?q=cache:uTd6CgsetfwJ:www.reefs.org/library/talklog/d_riddle_042698.html+Acropora+deep+water+color&hl=en&ie=UTF-8

http://reefkeeping.com/issues/2003-11/eb/index.htm

 

[Beckmola24]

That all is very helpful information. Thank you all.

 

[Ritsuko Nashida]

Thanks for the references, they made for some interesting reading!

 

[Beckmola24]

So with my halide unit, will I be able to keep pretty much every sps and clam?? Should I think of upping the wattage or not??

 

[The Apprentice]

Stay with the 250watt

Becky
I currently have 2 tanks with 250 HQI PFO lighting units. One with the double ended lights and one with the mogule bases I think 250 watts is just perfect just enought to get the light to the bottom and not to much to eat up the power bill, I know some of the members of the mid columbia group that are giving up the 400 watt units and going back to 250 watts
I hope this helps...Jeff
P.S. the Big tank with mogule bases have 20K on each end with a 10K in the center
My double ended hood has 2 15K lights ...

So with my halide unit, will I be able to keep pretty much every sps and clam?? Should I think of upping the wattage or not??

 

[Ritsuko Nashida]

With your 250 watt HQI /T-5 set up using 10K bulbs...you should be able to keep just about any SPS/Clam that you want as long as they have high light requirements. Changing to a 20K bulb might make your corals more florescent under that lighting but growth in all probability would slow down and you would have a blue wash to your tank. If you like that look then thats okay. But between 10K and 20k I would stick to 10K. If I had a tank like a 135 with three halides over it I might go to a 20K inbetween 2 x 10Ks. This is just my opinion though. Boy you really started a thread on a sensitive topic here though. I am suprised this hasnt gotten to be a heated debate!

 

[reedman]

Becky,
I think you will find that based solely on lighting you will be able to keep any of the SPS that you like. The only exception might be the deep water types unless you can fins some area low in your tank (too much light for some).

I'm running 2 250W 10K bulbs and 2 36" VHO actinic on my 75 and I've been able to keep anything I want so far, and I have a variety of SPS.

 

[Scooterman]

I know that the longer the wavelength of color the shorter the frequency, so you would lose colors on a reef in corresponding order; red, orange, yellow, green, blue, indigo, and violet. Blues and purples penetrate the water the deepest because of their higher frequency. So what I'm asking now is what color spectrum matches up to the Kelvin number on the bulbs? If possible I would like to have a happy medium. I would like to grow corals, in moderation, and have them look nice.

A few points enough to hurt the head reading lol!

Wavelength is the distance between the crest of one wave and the crest of the next wave.
Frequency is the number of waves that pass by at a point each second .
Shorter wavelength means greater frequency for a wave.
Frequency of a wave is the number of waves .

http://www.usbyte.com/common/approximate_wavelength.htm

http://www.personal.psu.edu/faculty/s/b/sbj4/aquarium/ballast%20comparison/ballast-comparison.html

http://reefkeeping.com/issues/2003-11/eb/index.htm

http://www.reefs.org/library/talklog/d_riddle_042698.html

 

[Hooked]

Becky,

You've got a great set up and unless you want more a blue look, you should be happy with the 10k bulbs. Everyone has covered the technical side of this thing, so just let me say, I have 2 - 250w DE over a 90 gal and I'm keeping clams and sps. I recently switched to the HQI from Iwasakis and I can already see the blue coming back in some of corals that had lost it. You really don't need a higher wattage bulb on that tank. The higher wattage will also generate more heat and burn more electricity.

HTH