View Full Version : So you want to know about lighting

11/29/1999, 01:13 PM

It is pretty obvious that you have an extensive background in lighting. I was hoping that I could lure you into a thread where all the lighting experts(or hobbiests, it doesn't really matter) out there, could teach those of us struggling with technical questions a thing or two. I don't want to compare bulbs manufacturers or types, but rather I am looking for explinations on some terms.

Here is a list of questions that I am hoping someone can answer;

What is the difference (besides wattage, output. cost, etc.) between VHO, HO, and NO bulbs?
Is it true that VHO bulbs are desgined for cold weather applications?
Can you describe the naming convention? (i.e. what is a T-12 vs. a T-8 connector and why is it important?)
Any information on PowerCompact lights?

Can you define the following terms and give an idea of how they apply to us as reefers?:

point-source lighting
Kelvin temperature

Okay, so I drew a blank at this point. I am sure that I am forgetting something. Any and all input is appreciated.


11/29/1999, 03:49 PM
NO lamp – 430 Ma
HO lamp – 800 Ma
VHO lamp – 1500 MA
VHO lamps were made for outdoor signs like Burger King and such
These signs needed a bright source that would not melt the sign
These lamps have mercury amalgams that hold the vapor pressure
of the mercury constant over a wider range of temps. Target vapor pressure is 1.07 Pa(0.00016 lb/in2)
A rule of thumb is that a NO lamp looses 1% of light output
for every 2F you deviate from a bulb wall temp of 100F or 77F ambient air
a longer bulb is more efficient. Peaking at about 8’ long.
This is where the power compacts derive their advantage, they simply
take a 4’ lamp and bend it into a 2’ space . The difference between 4’ and 8’
in efficiency is 5 lumens per watt.
One thing to be aware of is that high temps can alter the electrical properties
of the lamp, this may result in more current through the lamp. This will make it look as bright as it would at the proper temp but it will shorten
the useful life of the lamp.
Fluorescents all work on the following principle(except UV sterilization, it omits the phosphors)These numbers are based on a magnetic ballast
100% input
Arc is struck,
3% is visible
53% is UV at 253.7 Nm.
18% light
35% heat
44% heat
total heat is 79%(37% of this is infraRed)
total light is 21%
These numbers vary with the phosphor quality and you may get up to 23% light (according to one manufacturer)

Fluorescent lamp ballasts have different specifications which determine the
intensity of the lamp. The ballast factor is a huge number that is rarely listed.
Example: a lamp is rated at 1000 lumens, a ballast factor of 0.80 will give you 800 lumens out of the lamp. Most ballasts at a DIY store have a 0.8 to 0.9 ballast factor. Electronic ballasts can have a ballast factor over 1.00 but not higher than 1.25.
Current crest factor affects lamp life. A pure sine wave has a factor of 1.41
a good ballast should be 1.7 or lower.
Electronic ballasts are commonly operating about 25KHz give or take 2KHz. This puts them above the range of hearing but the lower it is the less interference it produces with other devices.
There are many others but they don’t come into play much :)
Lumen/Par/Lux :
Reference: IESNA Handbook-Sunlight about 6500K on a clear day 10,000 Footcandles on a cloudy day 1,000 footcandles
10 footcandles = 1 lux
How to measure light, Big argument. Lumen/Lux is a measurement that is
color corrected to human eyesight. 555nm is the peak of human visible response, that is the ugly green yellow color some fire engines are being painted.
Example: a multiplier of 0.004 is used for a wavelength of 420 NM (blue color) where the ugly 555Nm green has a multiplier of 1.0002. PS all the light in this wavelength give a max of 683 lumens per watt
This is why the term Efficacy is used and not Efficiency. Par is a measurement that was created for farmers dealing with land based plants.
Bottom line here- watts in, watts out. You get so many watts of light out in
different wavelengths. This is how the manufacturer produces the spectral curve that is sometimes seen on the package or in the glossy ad. the Lumen/Par/Lux numbers were calculated to make a quick accounting like comparison of lamps. Face it there is a huge market for lamps with the human eye as the target audience. This is the way that HPS lamps came into being. There is no magic here, the same number of watts of light output compared to a MH it is just that the eye peaks near the yellow of the HPS lamp.
CRI/ Color Temp(there are lies, damn lies, and then there is marketing) :)
Start off with a quote from the IESNA(Illuminating Engineers Society of North America)
“The application of the color temperature method to deduce the spectral distribution from other than incandescent sources even in the visible region of the spectrum will usually result in appreciable error. Color temperature values associated with light sources other than incandescent are correlated color temperatures and not true color temperatures”
a color temp number is meaningless unless it has a CRI number attached to it. A simple analogy is that the CRI is the grade the lamp got. You can call a fluorescent or MH lamp a 6000K 7000K or 8000K. Same lamp, but the CRI will be different for the different color temps. In my business the stated color temperature is the one that has the highest CRI. I feel that the aquarium trade has pushed for a higher color temp and the advertisements have reflected that. Same lamp but its Correlated Color Temperature is stated differently. Some spectral charts are very discontinuous, (has a lot of peaks and valleys) Who is to say it is a 6000K or a 10,000K lamp? Without a CRI number –nobody- The best way to tell what lamp will serve you reef best is to get the spectral distribution graph, and the value that is being used for its percentage base.
(Then get a biologist to tell us what wavelengths are best for the photosynthetic process and target those wavelengths)

Steradian is a solid angle:
The solid angle subtended at the center of a sphere by an area on the surface of the sphere equal to the square of the sphere radius.
this is the basis for the footcandle.
A ballon(radius 1 foot) with a 1 candela source at the center has 1 footcandle on 1 square foot of its surface. ( the source is emitting light at the 555Nm wavelength so it takes 1/683 Watts/Steradian to get a footcandle)
What a tangled web we weave? :D

In my profession a light is considered a point source when the opening of the light fixture is 1/20 the distance from the fixture to the work plane. Example: a downlight in your house with a 6” wide opening needs to be 10’ above the table to be considered a point source. This comes into play when we use computer programs to calculate light in a space. For reef tanks we are looking for the cool shimmering effect , which does not require a “true” point source. Remember that the sun just looks smaller. We are pretty small compared to the sun(that is one big lamp)

My opinion is that there is more light to be gained from the fixture then the lamp. The reflector and the lens can have more impact on the amount of light that gets to the corals then the lamp. Turn off the room lights and leave just the tank lights on. all the light that spills onto the floor is wasted IMO.
It is complex to make a reflector, and a parabolic lens is expensive but they work well. directing the light to the creatures is where the most efficiency can be found.
Thank you for your time and have a good day

I'm so skeptical, I can hardly believe it!

11/29/1999, 04:52 PM
I want to start this out. Hopefully, several of us can say this in different ways.

>What is the difference (besides wattage, output. cost, etc.) between VHO, HO, and NO bulbs?<

NO or Normal Output tubes conducts 400 ma current.
HO or High Output tubes conducts 800 ma current.
VHO or Very High output tubes conducts 1500 ma Current.

Think of it as 1X, 2X, 3X. output.

The differences to make a tube VHO (or HO) rather than NO is a different filament and minor differences in the gasses in the tube.

>Can you describe the naming convention? (i.e. what is a T-12 vs. a T-8 connector and why is it important?)<

T-8 is a 1" straight tube. the 8 refers to the number of eighths the diameter is. eight eighths is an inch.
T-12 is a 1.5" strait tube.
Its important to know which endcaps to use.
Some of the energy saving designs are T-8, while all the VHO designs are T-12.

>lumen< - This is a measure of the total light produced by a tube. Its important to note that its weighted to human vision, not the
needs of reef life. In other words, is there enough yellow light to read by?

>lux< - This is measure of the light actually irradiating (striking) a surface. Since lux is lumens per square meter, the same
weightings apply.

>Kelvin temperature< Light color is compared to a "black body" at a given temperature, measured in Kelvin. For example, Noon
direct light is said to be 6500K. IMO, this number is virtually meaningless unless the CRI is also given. 4100K (CRI > 90) is quite
yellow, while 14,000K (CRI > 90) is visibly blue.

Trivia, Kelvin is in reference to absolute zero, thus is not a relative measure. Only relative temperature measurements are referred to
as degree.

Actinic lights put out basically monochromatic (blue) light. Matching it to any Kelvin rating gives a very low CRI, making the match
worthless However, as an arbitrary convention, Actinic light was defined as 7100K for marketing purposes. This was before there
were any lamps above 6500K to indicate the lamps were blue. If it were done today, they would be given a 22000K
rating. (note, still no CRI)

This is a number that tells how good a color temperature rating is. CRI of 90 is indistinguishable from a black body of the rate
temperature, while a CRI of under 50 is meaningless. A CRI of 75 means that there will be some minor visible differences, but it will
be closer than a black body of any other temperature.
Think of the CRI as a marketing alert. If its present, the color temperature is credible. If its absent, marketing rather than fact is
talking. In various discussions, one 6500K MH has been marketed as a 10000K, because no CRI's were given,
who is to say which rating was correct.

>PAR< - Photosynthiticly Active Radiation.
This is a different measurement of light. It doesn't value yellow light more than red or blue. The good part is it doesn't give extra
credit for producing worthless light. The bad part is that it still counts worthless light. To convert LUX to PAR, a rough guess
would be to divide by 50. This is the best measurement of light for our reefs, even if its still flawed.

I am sure I have missed something.



[This message has been edited by DougL (edited 11-29-1999).]

Larry M
11/29/1999, 04:55 PM
Here's a related (I think) question I have: Which light meter (par or lux) do we want to use to check our lighting, and why?

Larry M

View a list of RC Member's websites at:

11/29/1999, 05:01 PM

I am humbled! Good job on your explanation!


11/29/1999, 05:10 PM
Larry M
I think a biologist needs to tell us what spectrum the photosynthetic animals respond to best. I think I rember but I am not sure so I wont say. Given what I think the range is the PAR meter seems to be better than the lux meter.
I am still a large fan of using the spectral curve. I am confident that we will not produce 10,000 fc (ie overlight a tank)
I made the reference to what has been measured for daylight on a clear day because I find it interesting that some people are afraid of to much light.
IMO the best lighting system would be the introduction of natural light. And depending on where you live(I am in Wisconsin, gets dark at 5:00PM :D) you may need to supplement the photoperiod.
thank you for your time and have a good day

I'm so skeptical, I can hardly believe it!

11/29/1999, 06:16 PM
So Badgers, what lighting system do you use on your reef?

just curious,


11/29/1999, 07:16 PM
AM I Glad You Asked! :)
I just got a 110 XH.
I am building a hood with 2(400Watt) and I am going to experiment with the designer color blue lamps from venture lighting. I have the spectral charts for these blue lamps and they seem to peak at what I consider to be a good wavelength for photosynthisis. I will post a thread when I see what it looks like. I will most likely use 175W lamps for the designer color lamps. I am afraid they will be to blue. the 400 W are GE 6000K 90CRI bulbs. These must be installed horizontal, no pendant fixtures.
thank you for your time and have a good day

I'm so skeptical, I can hardly believe it!

11/30/1999, 01:02 PM
All, thanks for the replies so far. You guys have really helped to make this discussion very indepth. I would like to add the following:

CRI = Color Rendering Index. This number reflects the ability of a particular light source to reproduce a complete spectrum of light. Natural sunlight has a CRI of 100, meaning that it produces 100% of the color spectrum. I think that with this in mind, it makes the relationship between CRI and Kelvin much more apparent.

More Questions:

Are the given amperages for the different fluorescent lights running, or starting values?

How can one calculate the effect on lighting intensity a filter of some sort has? What if any experience do you have with lighting filters?


You said: "The difference between 4’ and 8’
in efficiency is 5 lumens per watt."

How does this apply to Power Compact bulbs? Do you consider a 4' PC to be an 8' bulb?

You said: "A rule of thumb is that a NO lamp looses 1% of light output for every 2F you deviate from a bulb wall temp of 100F or 77F ambient air"

What abouy the other bulb types (VHO, HO, and PC)?


You said: "The differences to make a tube VHO (or HO) rather than NO is a different filament and minor differences in the gasses in the tube."

Can you be more specific? What are the filaments made of? What are the variations in the glass?

I am sure that I am leaving something out, but I have to end here. Again thank you all.


11/30/1999, 04:15 PM
The comment about the differences was based on an email from ASH (Andy from Icecap).

I think badgers did a very good job of describing the vho gas mixture in his post.
I assume that the VHO filaments draw more current in order to ionize the gasses, but you know where assumptions get you.
However, its reasonable given the extremely short life of NO tubes on VHO tar ballast.

Hope this Helps;



11/30/1999, 05:15 PM
How does this apply to Power Compact bulbs? Do you consider a 4' PC to be an 8' bulb?
the bulb length is the length from one end to the other. if it is 4' down and 4' back then it is 8' long. some compact fluorescents have four visable "runs"
Technical- the electodes have losses. these are "fixed" losses. Economics of scale come into play. The more phosphor(lamp length) per electrode the better up to a point.

filters- they remove a specific spectrum of light. if your filter passes blue light(looks blue) then it is not reducing the blue intensity. Each filter is specific as to which wavelengths it removes. It seems that some wavelengths of light do not help photosysthisis at all so removing them is an asthetic choice. Filters remove some light energy how much and which frequencies is dependant on the filter.
Are the given amperages for the different fluorescent lights running, or starting values? Running values(in RMS,root mean square)
natural light provides all frequencies of light but in different proportions. (US air force 1965 study)
555nm is the most intense wavelength from the sun(it is no accident that our eye peaks at this frequency) about .14watts/cm2
oxygen "filters" light around 790nm.(no accident that this is the upper bound of our vision) 790nm provides about .025 watts/cm2
ozone filters the uv and at 380nm natural sunlight provides .01 watts/cm2
this is an old study but the sun has not changed much(maybe less ozone, but that is another topic)
this goes back to a previous point, watts in - watts out.
this light provides power to the photosynthetic organisms.
the sun is not a flat source where every frequency is provided in equal amounts.
The CRI is (CCT)correlated color temperature dependant. An incandescent has a CRI of 100 with a CCT of 2700K.
A clear day seems to have a CCT of 6500K and is defined to have a CRI of 100.
above 5000K a black body radiator is no longer the reference. The reference becomes sun light at different times of the day.
Example- sunrise/sunset the CCT is about 2500K thats why it looks red.
The IESNA has something called standard illuminants. There is a slew of them. This is how the CRI is arrived at. Compare the lamp with the standard illuminant of a given CCT. How well the lamp compares with the standard is its CRI 100=100%.
VHO,HO bulbs have a much larger operating temp then NO bulbs. VHO lamps with MH in a hood will do better then NO lamps in the hood. I have not seen test data on the PC lamps, I do not know.
DougL is correct that the lamps are physically different:
Filiments are coated with an "electron-emissive material"
NO-some are a cold cathode with a cathode fall of about 50V(some NO have a hot cathode)
HO, VHO -hot cathode have a coiled-coil of tungsten with a alkaline earth oxide coating operating at about 1100C this exibits a cathode fall about 10-12V. What exact alkaline earth oxides are used I don't know.
the point of the filament is to emmit electrons(strike and sustain an arc)
A fluorescent is hermetically sealed. the vapor pressure is a function of how much current (heat) is produced in the lamp. the VHO lamps take this into account when built. This is why I stress getting the a ballast designed specifically for your lamp. A ballast will light many different lamps but you may be shortening the lamp life or (better case) running a lamp very lightly. In some cases things may be close enough(this aint rocket science) but in others it may not. Will the lamp light, yes. Will it have the efficency you thought? maybe yes most likely no.
the more current the more uv light is produced making more light to a point. The concept of diminishing returns. There is a limit on how much current you can put through a lamp.
I am going to change my name to ramblin' :D
thank you for your time and have a good day

Library may have the Lighting Handbook 8th edition ISBN 0-87995-102-8.PG 197-236 talks of the lamp construction. All of chapter 2 talks about measuring light(steradians definition has a good graphic)
The book is slanted towards human vision(lumens/footcandles is used everywhere)

I'm so skeptical, I can hardly believe it!

12/01/1999, 09:43 AM
Awesome thread you guys!!!

Badgers and/or Doug,
I am confused about how much of the heat that is transferred from the lamp to the tank is determined by the bulb type and how much comes from the ballast type. Could you elaborate on the relationship between different types of ballasts and the heat output from a fluorescent bulb? Will a better ballast make the same bulbs run cooler? For example, will an Icecap electronic ballast running NO bulbs give off less heat from the bulbs to the tank than a Coralife electronic ballast running the same NO bulbs? Also, how do you predict how much more heat will be transferred from the bulbs to the tank by that same Icecap ballast running NO, VHO or PC bulbs? I'd like to figure this out before investing in new lighting for my already overheated tank.

Thank you very much,

12/01/1999, 12:05 PM
Ewan- I am very interested in the MH electronic ballasts. I will wait to answer untill I see the test data that I have asked for from GE. Here are some interesting points.
MH does not gain from higher frequencies, some MH electronic ballasts are DC.
I think that the electronic ballast should help lamp life considerably, if the ballast can take it. MH is more complex then fluorescent. MH is sensitive to the way it is mounted. a universal mount MH lamp gives more light when horizontal then vertical(pendant). The rating quoted is given from the horizontal position.
The electronic ballast should allow a great deal of control over the lamp, which can be a great advantage. But, someone can screw it up and the electronic ballast might not be much advantage.
Ballast losses-(advance core and coil)
400W-458W input
250W-295W input
175W-210W input
70W-90W input
thank you for your time and have a good day

I'm so skeptical, I can hardly believe it!

12/01/1999, 02:07 PM
Thank you for your time and your reply. Icecap also claims that you can run NO lights off their VHO ballast and get higher output from the bulbs. Is there validity to this claim? Would it also run hotter then? Also, can you compare the relative amounts of heat that would be generated by NO (40 W), VHO (110 W) and PC (96 W) bulbs if each type of bulb was run on the same type of electronic ballast?

Thanks again,

12/01/1999, 03:10 PM
I can't say much about Icecap. I can't get any info from them. It is concievable to determine what lamp is connected by monitoring the volt/amp characteristic, and then adjusting the output accordingly. Yes you can run a NO on a VHO ballast and it will be bright.
If the ballast factor of the electronic ballasts are the same the VHO will give off a higher percentage of heat then the NO or the PC. the NO and PC will be similar in percentage. The VHO is less effient then the NO lamp, due to the current density.

I'm so skeptical, I can hardly believe it!

12/01/1999, 04:57 PM
I have heard recently that Blueline will be marketing electronic MH ballasts soon in 400W. These ballasts will not require 'tuning' to the individual bulb as does IceCap. This will give more versatility to those that may want to change lamps later. Champion has been testing these setups for about 4 months (personal communication) and state they show no flicker or other problems that have been associated the electronic IceCap MH ballast.

Have you heard of this new product and what are your impressions? What would be the result of not 'tuning' the electronic ballast to the individual bulb...is 'tuning' the magic that makes IceCaps brighter, if in fact they are? Would one still get a benefit if using an electronic ballast that is not 'tuned'.

Thank you. Please feel free to ramble.


12/01/1999, 06:22 PM
With MH Icecap may have something with the tuning that gives them an advantage. Most bulbs are designed to comply with the ANSI standard. The 400W MH you speak of is designed to this standard so it should run any lamp to its ratings. The light source in a MH is the Halides themselves, which is in different proportions and sometimes different halides to give different colors. These halide combinations will have different electrical characteristics for the arc. "tuning" a ballast for a given mixture should give better then rated performance for that lamp only. I agree with you in that I would want a ballast that can run any 400 W mogul base lamp.
I will try to track down what some of the common halides are when I get back to the office tomorrow. PS This is how venture makes there master color series of lamps be a specific color.
Please, email me any info you have on this ballast I would like to research it.
thank you for your time and have a good day

I'm so skeptical, I can hardly believe it!

12/01/1999, 10:47 PM
WOW Badgers! You really know your lighting. I am postrating to you as i write this :) So tell us, how is it that you're involved in this profession, if i may ask? Thank you so much for taking the time to enlighten us (no pun intended).

Guys, how about Motorola? Every now and then i hear someone mention their MH electronic ballasts. Does anyone have any info on them other than what is listed on their web site?


www.homestead.com/johnnymok (http://www.homestead.com/johnnymok)

[This message has been edited by Flamehawk (edited 12-01-1999).]

[This message has been edited by Flamehawk (edited 12-01-1999).]

12/01/1999, 11:42 PM
Wow... here's all the information on lighting. This should be edited into a Fama article, to help out beginners in their lighting decisions. Badgers, you should consider doing a talk on #reefs. Everything I found about lighting in the last 4 years in the web is right in this message.

As well, I have a question maybe someone can answer. Would there be a considerable difference between a 70w electronic MH ballast and a 70w core+coil ballast. By considerable, I guess I mean longer bulb life, significant difference in light output, etc.


12/01/1999, 11:51 PM
A fluorescent gives off 79% of its input as heat. by reducing the current through the bulb the bulb will run cooler. In general elctronic ballasts can get 20%-25% more light at a given current. Or to run the bulbs cooler the electronic ballast runs at a lower current to match the light output of a magnetic ballast. This is test results of the electronic ballast that is UL listed. Icecap claims to have some wiz-bang secret that boosts the lamp efficency by more then 25%. I am not convinced of Icecaps superiority over other electronic ballasts. The limiting factor is simple physics. I don't care how high the frequency is in an icecap ballast. Tests have been run up to 120KHz, after 25KHz no gain is achieved. At the higer frequencies you run into RFI interference. 90KHz is the begining of the radionavigation band.
Bottom line. electonic ballasts can get more light at the same current or the same light with less current.
Note. Ever wonder why they make NO,HO,and VHO, and not just VHO everything? VHO exibits poor lumen maintenance. This means the color shift and reduction in intensity is more pronounced in the VHO lamps as compared to the NO lamps. The more intense UV in a VHO breaks down some phosphors. This is what causes the color shift. Some phosphors are more resistant then others. That is why the color shifts, and the intensity drops off with time.
thank you for your time and have a good day

I'm so skeptical, I can hardly believe it!

Reef Junkie
12/02/1999, 06:01 AM
Thanks so much for all the time and info you've just given all of us. I'm also very interested in the Electronic MH and wonder if it's worth the extra $ to buy it? I'm currently runnning 2 400 watt MH bulbs, 65k if that even matters? I just bought the Iwasaki 400watt 65K bulbs. They appeared yellow the first week, but are now turning white as they "break in", is this normal? I normally run 10k bulbs, but have seen too many tanks with 65k bulbs and much more colorful corals. As an aquarist, what is your take on this? Do you know about/like the Iwasaki 65k bulbs?


12/02/1999, 09:14 AM
Reef Junkie: the breakin period is normal. Every MH has it. Some manufacturers pre burn their lamps but these cost more. Burn in should not take longer then 100 Hrs max. I only deal with GE, Phillips, and Venture MH lamps since I have a professional relationship with the dealers and I get a good price.
Everything comes down to money :D
I think that if costs were equal MH would be a better choice for a reef tank. But MHs are more expensive(PS Aquarium trade is really high in price) so people turn to fluorescent. I have a fluorescent fixture that I made for my sump. I did not need a lot of light for some live rock an some macro algea. IMO everything has its use. Fluorescent are a cost effective way to achieve efficient medium light levels.
Based on my limited info. reef creatures need a high level of light intensity.
Reef Junkie: When comparing lamps ask what the CRI is on each lamp. Studies indicate that light incident on the surface of the earth is about 6500K CCT. A CRI of 90 will give you a full spectrum source. A lamp with a CRI of 60 will have gaps in its spectrum which may or may not be "bad" for the photosynthetic creatures.
thank you for your time and have a good day
How a MH lamp works:
the center of the arc tube is where the arc is. Here it is so hot that the metal/halide breaks down and the metal emmits light at its radiating frequency. The metal and halogen move toward the cooler arc tube where they recombine(this is why MH are position dependant, it is convection that moves them). now the cycle begins again.
common halides(this is not nearly an exhaustive list)
Scandium and sodium iodides
dysprosium, holmium and thulium rare earth iodies.
the Rare earth mixture produces about a CCt of 5400K which can be tweaked.
indium will give more blue when added to the mix.
UV is emmited and some lamps use a phosphor coating(like the fluorescent) to turn the UV into visable light.
About starting, above 150W the starting method is similar to mercury vapor lamps, with one exception. depending on the halides present it may take a larger starting voltage for the MH lamp.
When starting the reason you sometimes see differnt colors is that different halides vaporize at different temps. The restrike time is simply how long it takes for the halides to cool to lower the vapor presure of the gas. There has been some work done on restrike that eliminates the need for cool down. This helps me more then you. When I design a building with a generator to power the lights it takes 10Sec for the generator to start and get running. The MH will have gone out. When the generator picks up the lights I need the MH to come back on right away. My point :D dont spend the money for instant restrike lamps on an aquarium.
Also, if you are interested in dimming a MH keep this in mind. You need to turn the MH up all the way and keep it there untill all the halides are vaporized before you can dim it down. If you don't you may not get the right CCT or intensity. There is a latent heat that needs to be provided to change the state of the halides to a gas.
I am ramble man!!! :D

I'm so skeptical, I can hardly believe it!

12/02/1999, 09:44 AM
O.K. This is a great discussion, but I am so lost it's not even funny. What does all this mean as far as what lighting is best to use on our tank in general?


members.xoom.com/KoryFox/index.htm (http://members.xoom.com/KoryFox/index.htm)

12/02/1999, 10:08 AM
It doesn't really relate Fox.

I don't mean to be disrespectful, and on a certain level the discussion is interesting.
But it's like going to the pharmacy with a headache and getting a dissertation from the pharmacist about the pharmaceutical uses of rain forest plants. You leave with a certain academic understanding, but your headache is still there.

12/02/1999, 10:35 AM
Actually, I think this discussion gave me a headache :). Im with ya Fox, totally lost. :)

12/02/1999, 12:04 PM

Like I said, the discussion is great, but the majority of us do not understand electricity/lighting the way you and the others discussing this do. All I'm asking is, what does all this equate to when I make my next lighting decision? That's all.


members.xoom.com/KoryFox/index.htm (http://members.xoom.com/KoryFox/index.htm)

12/02/1999, 12:19 PM
what this all means:
MH are sensitive to mounting position.
Fluorescents are sensitive to heat.
Color Temp is actually Correlated Color Temp.(CCT)
CCT numbers are meaningless without a CRI number.
The reflector and lens plays a large part in how well the reef is illuminated.
6500K is about the highest CCT in nature at a CRI of 100.
For high intensity in small spaces MH is the best bet(800Watts in a 4' long space)
Lumens and Par are not very helpful in targeting the the main "pigments used in photosynthesis, chlorophyll a & b, absorb light in the 440-460nm and 640-660nm range"
thank you for your time and have a good day

I'm so skeptical, I can hardly believe it!

[This message has been edited by badgers (edited 12-02-1999).]

12/02/1999, 12:58 PM
What about the distance between the lamps and the water surface? What are the factors one should consider when choosing/designing a hood regarding how high above the water surface a MH, PC, VHO or NO bulb should be?

Reef Junkie
12/02/1999, 09:14 PM
Thanks for the info. I'll try and get in touch with the manufacturer of the bulbs I just purchased. Now I know why the tank looks so yellow when the lights start up. So knowing that MH bulbs need to reach a peak temp before dimming them, what would be the peak temp for a 400 watt bulb. I'm also assuming you're talking about Electronic MH ballast? Also, Ditto to what Robert asked.


Larry M
12/02/1999, 09:49 PM
A lot of this is over my head too, for right now. But I still like to see in-depth discussions like this because someday as I progress in the hobby I might want this information. What seems like Greek right now might not in a year or so. It's nice to know it will be in the archives when we want or need it.

Larry M

View a list of RC Member's websites at:

12/02/1999, 11:40 PM

sorry that this is too deep for some of you.. I actually find it to be very interesting. Although some (alright, most) of this is way too deep for the average aquarist, and the information is all but useless to the most die-hard lighting freaks (yes, i'll admit, I am a lighting freak), it is VERY helpful and informative, and I am getting some really great info here. I like the fact that I now know enough to feel compitent going to any lighting store and getting EXACTLY what I need and not having to pay custom sealife, or PFO, or other big name, big dollar, fish suppliers.

go badgers! thanks for all this great info! I hope that when all is said and done to compile this and other lighting info into a great FAQ that will encompas all user levels from the novice, to the most hardcore lighting experts.. keep it up!


The quest ( and the questions) continues...
www.iag.net/~vigg (http://www.iag.net/~vigg)

12/03/1999, 08:12 AM
RobertK the distance is a function of how the light is dispersed. For a simple lamp above the water, the higher up the more even the light. Also, the higher up the less intense the light will be. For some people raising the lamp reduces the heating effects.
ReefJunkie:The operating temp is lamp specific. This is why I believe Icecap can get more out of a specific bulb by "tuning" the ballast for a MH lamp. You know when the lamp is at its operating temp because the light will have its color. Not all dimming ballasts are electronic, but most are.
"I'm also assuming you're talking about Electronic MH ballast?" what I have said about MH thus far is applicable to both electronic or core&coil. But, it would be easier to "tune" an electronic ballast for a MH lamp IMO.
I called Perry about the ballast and he said it would be about 3 weeks before he could send me any test info on the ballast.
thank you for your time and have a good day

I'm so skeptical, I can hardly believe it!

12/03/1999, 09:48 AM
badgers, Thank you very much for meeting the challenge thread. Great Information! I would like to chime in with some more questions here.

What is the difference between Metal Halide and Mercury Vapor?

Why does a Metal Halide bulb running on a Mercury Vapor ballast smell?

Could you help to explain how a hobbiest would know which fluorescent ballast to use with a particular bulb? For example, why does a ballast designed to run HO bulbs, run a PC bulb? I know that I can go to the Advanced website, and look up ballasts by giving specs, but I am confused as to what some of the terms are. (The site is having technical difficulties, or I would add some of the terms.)

Okay, that's it for now. I will add more later.

Thanks again,

12/03/1999, 03:50 PM

I would like to add one more question to the list. OK, maybe two or three ;)

I have M58 metal halide ballasts. I was thinking about using the GE bulbs mentioned in this thread. GE lists these bulbs as requiring M80 ballasts.

Is there much difference between M58 ballasts and M80 ballasts?

Currently, I have Iwasaki bulbs on the M58's and I know I need to either buy some H37 ballasts for the Iwaski bulbs or find some new bulbs.

After looking at some bulb and ballast info in appears that the Iwasaki 250 watt 6500K MH bulb with a H37 ballast is more efficient than the GE 250 watt 6000K MH bulb with a M80 ballast.

The H37 ballast has input wattage of 280 watts and the light output(with Iwasaki bulb) is 14,000 mean lumens with a rated life of 9,000 hrs. The M80 ballast has input wattage of 295 watts(I think) and the light output(with GE bulb) is 13,300 mean lumens with rated life of 10,000 hrs.

It seems counter intuitive that a bulb designed to covert MV to MH(Iwasaki) would be more efficient than a MH bulb(GE). Am I missing something?

Sorry for the ramblings. Is it obvious that I'm confused ;)


Larry M
12/03/1999, 04:20 PM
badgers left today to go on a cruise and will not be back until Dec 13 or 14. The nerve of that guy!!

Larry M

View a list of RC Member's websites at:

Larry M
12/04/1999, 02:24 PM
Since there were some questions here regarding IceCap lighting, I have invited Andy Howard, President of IceCap to participate. We'll see what he has to say.

Larry M

Northern Reef (http://www.homestead.com/larry_reef/index.html)

12/04/1999, 04:52 PM
I don't know if I should thank you for the invite. (It's less threatening
with badgers on vacation.) I agree there's a little much in the way of
factual overload in this thread. Regarding IceCap products I'd add the MH
ballasts use high F to create and maintain the arc constantly, a
conventional ballast runs at 60 to 120 Hz, turning on and off that many
times per second. IceCap also starts a lamp at < 1KV vs 3 to 5 KV in a
conventional ballast. Both differences should favor a longer lamp life with
our ballast. I'll rejoin tomorrow for ....

I find it hard to believe there's still a doubt about our VHO ballasts abilities with NO lamps.


12/04/1999, 05:07 PM
Hey Andy,
How about an electronic 400W MH ballast from IceCap? This would be a winner for sure.

Also, how about offering the ability to buy the electronic MH ballasts untuned, i.e. would run any bulb? The need to pick your bulb 'for all time' makes the decision to go with your MH products difficult at best. Also, how much is re-tuning, should one decide to buy your ballast and switch bulbs later?

Thanks for participating in this discussion.
Your 660 VHO has been runnning on one of my reefs flawlessly for years.


12/04/1999, 07:22 PM
There are two projects ahead of a 400W-MH, at least. The 250-MHI (for the Iwasaki 250W 6.5K) is our brightest option we now offer. The next MH out will be a 150-MH with restart and other new features.

As far as the tuning issue, we are looking into a self-tuning ballast down the road. The differences between many (Most)175W and 250W MH bulbs is so small we could offer a small one-turn knob and cover most of them, but it always seemed like giving up on hitting 'the mark'. I've since learned the problem has to do with two different challenges. One is the variability in bulbs as only the automated bulb factories turn out cookie cutter, identical products. The other is bulb companies are free to change the formula without notice. (In addition, our own product varies due to minor fluctuations in parts...) Certain bulbs like the Iwasaki 250 are in a different class and use unique parts. Recently, in dealing for example the with the new Coralife imported 10K bulbs, we're finding a minor change (tuning) in the Iwasaki ballast will likely be the answer. For the immediate, we retune or upgrade to current specifications at no charge (except for a change to an Iwasaki ballast). Conventional ballasts and other electronic ballasts that mimic conventional ballasts but in an electronic form, are not as sensitive to these changes as they blast the lamps to life and run them differently also. IceCap uses a technology similar to how it lights fluorescent lamps involving feedback between the bulb and the ballast.

I'd like some feedback on the 'knob' idea. It's is an option that would be easy to put in place.


12/04/1999, 08:17 PM
man what a thread!
My Q is this,
Im going VHO soon(Icecap 660 w\2daylight 2 actinic bulbs) from NO( 3 36" twin bulb shop lights) I could get 1 400w MH and an Advance ballast cheaper and run 2 NO's with it, but Im worried about heat and too little light befor and after the MH goes off. This is over a 36"x12"x22" tank
Oh yeah Im gonna do dawn and dusk w 2 NO actinics for an hour before and after the VHOs come on and go off, is this sufficent?
is it true that after 8 hours all MH bulbs do is add heat to the water( ie. the light is still on, but all the work is done)


my homepage (http://www.angelfire.com/on2/hesaias/index.html)

Larry M
12/04/1999, 08:28 PM
Andy--Why a 150w MH? It seems like there would be a lot more demand for a 400w electronic ballast.

Larry M

Northern Reef (http://www.homestead.com/larry_reef/index.html)

12/04/1999, 09:42 PM
I agree. MUCH more demand for an eletronic 400W ballast. Blueline is introducing one this month and it will sell big, I would bet.

I think the tune knob is a great way to go, when can I get one with this?

If not, are you saying if I buy the Iwasaki 250W MH ballast and want to switch to 10K's down the road there would be a charge? How much? There is a new Aqualine Bushke 250W 10K bulb that is supposed to be great.



[This message has been edited by elvisdoc (edited 12-04-1999).]

12/04/1999, 11:00 PM
"I find it hard to believe there's still a doubt about our VHO ballasts abilities with NO lamps." Excuse me for being a beginner amongst all these experts when it comes to lighting and for not being familiar with your products. I think what I was really wanting to know is if an NO lamp running on the Icecap VHO ballast puts out the same amount of heat (and light) as a VHO bulb would.
Thank you and have a nice day.

12/05/1999, 12:22 PM

Regarding the knob you mentioned, personally I would not be very interested in a 175/250 watt ballast.

I would be very interested in a ballast that could be user adjusted to a specific bulb. Just turn a knob to a specific setting for a specfic bulb. I don't know if this is possible but, I'm purchasing my third set of Advance ballasts. I had M80's switched to M58's and now I just bought H37's.