NO lamp ââ"šÂ¬Ã¢â‚¬Å“ 430 Ma
HO lamp ââ"šÂ¬Ã¢â‚¬Å“ 800 Ma
VHO lamp ââ"šÂ¬Ã¢â‚¬Å“ 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 8ââ"šÂ¬Ã¢"žÂ¢ long.
This is where the power compacts derive their advantage, they simply
take a 4ââ"šÂ¬Ã¢"žÂ¢ lamp and bend it into a 2ââ"šÂ¬Ã¢"žÂ¢ space . The difference between 4ââ"šÂ¬Ã¢"žÂ¢ and 8ââ"šÂ¬Ã¢"žÂ¢
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)
Ballasts:
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 donââ"šÂ¬Ã¢"žÂ¢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)
ââ"šÂ¬Ã…"œThe 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 temperaturesââ"šÂ¬Ã‚Â
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 ââ"šÂ¬Ã¢â‚¬Å“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?
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 6ââ"šÂ¬Ã‚ wide opening needs to be 10ââ"šÂ¬Ã¢"žÂ¢ 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 ââ"šÂ¬Ã…"œtrueââ"šÂ¬Ã‚ 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
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I'm so skeptical, I can hardly believe it!