10,000k vs. 20,000k

[bowfront26]

could someone pm an adress comparing MH bulbs. I have the 20,000k XM 250W HQI, and hate it... should i return it or get a different bulb like a 14,000k

[ODOG]

Would be easier to answer if you stated what you hate about.

[Cellenzweig]

I assume you're looking for something like this:

 

http://www.nano-reef.com/forums/showthread...&threadid=37337

[jaguilar]

bowfront26, check this page out. it compares almost all of the major brands of 250w mh bulbs. the only thing is that he tested se bulbs, not de. but it gives you a good idea as to the look of all the different brands and color temps.

 

http://www.cnidarianreef.com/lamps.cfm

[skeletor]

Did you let it burn in yet ? 20Ks burn real blue at first then settle into true color after a couple of weeks.

 

-skeletor-

[MarLooney]

still too blue IMO. i'd go w/ the 14,000k.

[jaguilar]

i agree with looney, i think the 14k's are a perfect mixture of both. not too white, not too blue.... it gives the appearance of a 10k bulb with actinic supplementation. i just ordered the hamilton 175w 14k bulb, and i can't wait to put it on my fixture.

[bowfront26]

Damn guys... youre starting to make me regret returning the MH. I really didn't like the look. I should have waited though. I'm sure I would have been happy with a 10,000k or 14,000k... damn it. #@%$... I was looking at someone pics of there 30g. cube with 250W MH 10k bulb. It looked awesome... oh well in the future I'll try it again.

Any of you guys have the same aqua medic light I was talking about at the beginning of this thread. It seems like a really good price for the package... could it be that it is less quality than other MH... just a thought( but I doubt it).

[brahm]

Out of all the bulbs i've owned, My 20k AB is the nicest bulb yet, It's a perfect crisp white in my opinion, not to blue, to yellow. .Doesn't really need any supplemtation although a single 03 wouldn't be bad to bring it some more of the flurcents in the corals.

[bowfront26]

Were you pleased with the bulb from the beginning

[Angel]

I have a 10K and a 20K (on two different tanks) and want to try a 14K to see the difference. I know I won't go 10K again and when time comes to replace that one, that is when I will probably try the 14K. I just don't like the look of the 10 on my tanks. My 20 took a little breaking in also, but you can definitely tell the difference.

[brahm]

well I bought the setup used, the bulb was 3 months old when I got it.

[sturuomo]

how about considering the colour spectrum your corals need?

 

Some info...

 

The spectrum or "temperature" of light is measured in degrees Kelvin (K). The Kelvin scale describes the color of a light source when compared to a theoretical "blackbody." Think of a piece of steel that changes color as it is heated. The Kelvin scale does not measure the light the steel gives off as it is heated; instead it measures the color of the light being given off. Color temperature does not represent the temperature of the light source. It merely defines the color given off in comparison to a blackbody radiating at the same temperature.

 

At 0 degrees Kelvin (equivalent to -273° Celsius), the theoretical blackbody emits no light. As the blackbody warms, it begins emitting red light. As the blackbody continues to increase in temperature, light wavelengths become more yellow, then green, blue, and finally violet. A candle flame on the Kelvin scale has a rating of 1800 K. Sunlight at noon, with a Kelvin rating of 5500 K, is typically referred to as full spectrum because it contains a blend of all colors throughout the spectrum. Reddish light has a lower K rating and color temperature, while bluer light has a higher K rating and a higher color temperature.

 

In nature, as light enters and passes through the first 15 feet of water, the red and orange wavelengths are absorbed by the water, increasing the light's K rating, and giving the light a bluer appearance. As the light penetrates to 30 feet, the water absorbs the yellow spectrum. And as the light continues past 50 feet, the water filters the green wavelengths, leaving just the blue and violet wavelengths. This results in light with the highest Kelvin rating.

 

To adequately illuminate reef aquariums 24" deep, plan on providing between 4 and 6 watts of light per gallon of water. Shallow reef aquariums (less than 16" deep), and reef aquariums specifically designed for low-light or non-photosynthetic corals and invertebrates do not require the intensities of taller aquariums. However, under no circumstances should you provide photosynthetic corals and invertebrates with less than two watts of light per gallon of water; they will not have enough light to survive.

 

Natural conditions have caused all corals and invertebrates to adapt to bluer light. Therefore, most lighting systems include bulbs that focus specifically on blue wavelengths. Fluorescent systems, for example, offer blue bulbs called actinic bulbs. While most corals and invertebrates thrive under blue light, most people find blue-lit reef aquariums rather unattractive. This aesthetic dilemma can be solved by combining an actinic light with a white light. Most reef aquariums thrive under a half-and-half blue/white light combination in which the white lights give light in the range of 8000 to 12000 K. This lighting combination gives corals and invertebrates the spectrum necessary for growth, in addition to the spectrum necessary for accurate color rendering within the aquarium.

 

How deep are these nanos? Cant be more than 18" Can't see why you require MH with all that wattage? Overkill.

 

I work on minimum of 4 watts per gallon. 6 watts is perfect. Power in this state costs 18c a kilowatt.

[Cellenzweig]

sturuomo,

 

Great explanation of color temperature. (It's carbon not steel, but that isn't really important). It's pretty difficult to find it explained so well in this hobby. I've found that most people have no clue as to how color temperature is derived.

[bowfront26]

That was a nice explanation. I think people are using to much light, it's more about bragging rights than providing your corals w/ enough light.

By the way I run a 400W MH on my nano cube. (i'm kidding)

[calvinci]

Why nobody mentioned about the PAR value? I thought 20K PAR is only half of 10K, the light demanding coral or invert might starve if simply switch from 10K to 20K without considering the PAR.

[MrAnderson]

Thanks for the post Sturuomo, nice to see someone take the time to explain things correctly for all the newbs out there...

 

"Natural conditions have caused all corals and invertebrates to adapt to bluer light."

 

What about corals growing near the surface, say 1-6 feet deep, that only see white (5500-6500K) light? Nanos are very shallow and this is the niche they reproduce. Why bother with actinics at all if you're not keeping deepwater corals? The white spectrum will have chlorophyll-stimulating wavelengths anyhow...

 

Coral guru Eric Borneman says he prefers 6500K for keeping most of his corals, but popular wisdom says throw in some actinic. I myself am torn between the two approaches.

 

Any thoughts/experiences?

[Undertheradar]

"How deep are these nanos? Cant be more than 18" Can't see why you require MH with all that wattage? Overkill."

- there is a simple reason. some corals need it. Think about it. Watts per gallon is a good rule for minimal viewing...esp with regards to freshwater swim tanks. But with reefs, it's very diff. watts per gallon is not a very good rule of thumb. lumens/PAR at a given depth is a much better rule. Using watts per gallon, a 70wattMH would provide 7watts per gallon for a 10g. A 75gallon could be illuminated with a couple 250wattMH bulbs...not even 7watts/gallon. But I bet you wont be able to grow any high light SPS like blue milli or pink acro, or a crocea clam under the 70watt-10gallon like you would in the 2x250watt - 75g. The intensity just isnt there. I have seen 150gallon tanks with nothing but 2x175watt bulbs and doing fine...and there are plenty of tanks out there that are small with ooodles of light...not just for bragging or blinding the wife...but for the corals. With watts per gallon, youre 1gallon would be fine under 7watts...nothing will grow under that little light (okay shrooms maybe)....its just too little. I find nanos need more light to have enough intensity to be on the same level as mini-reefs. I am finding 10watts per gallon, with a minimum of a 150wattMH to be my common practice.

And FWIW, all I ever use is halide now. It actually provides better ventilation and cooling than Power compacts with a shorter necessary photoperiod (also saving electricity) as well. This shorter photoperiod means less heat going to the tank, and this time can be scheduled after peak temps of the afternoon. and nothing beats the light. Did you know that the intensity of halides is 2x that of the same wattage compact?

 

"I work on minimum of 4 watts per gallon. 6 watts is perfect. Power in this state costs 18c a kilowatt."

-KWH. Killowatt HOUR. Where do you live man? Thats expensive. That still isnt too bad however. That means a 250watt MH can run for 6 hours (all the exposure you need unlike power compacts) a day and cost $.27 ... not bad.

 

"To adequately illuminate reef aquariums 24" deep, plan on providing between 4 and 6 watts of light per gallon of water."

- again, dont start the watts/gallon myth. please.