Explaining MH Lights

[BBReef]

I'm in the middle of planning out everything I need for a 150 gal Reef. I pretty know everything I need, but don't really understand how metal halides work. I looked at the new bulb compairison page (great idea btw ) and really like the way the 2x250 20k bulbs look. http://www.aquariumadvice.com/bulb_comp/mh_20K/SunnyX_MH
here are my questions.

what exactly does the different kelvin do?

when setting them up, does each bulb run off of a different ballast?

how long do the bulbs last?

would a 150 gal be better off with 2 x 400w or 3 x 250w? (the dimensions are 60x24x24)

whats the difference in euro made, german made, ect... bulbs?

what else would i need besides the ballast, sockets, bulbs, and reflectors?

sorry for all the questions, but thanks for any responses.

 

[Biggen]

I am a little rusty in my halide info, but I will try my best.

what exactly does the different kelvin do?

Kelvin is used when, in bulbs anyway, describing the color at which the bulb will emit when lit. When a black body (i.e. piece of metal) is heated to 10,000 Kelvin, it should emit an extremely white light. When the black body is heated to less than 10,000 Kelvin, the light it emits is yellower. The higher it is heated above 10,000 Kelvin, the more blue the light becomes. FYI, noon day sunlight is rated at 5500 Kelvin. So as far as bulbs go, the higher Kelvin temperature you select, the more blue in color the bulb will appear to be.

when setting them up, does each bulb run off of a different ballast?

Typically, yes. Every bulb uses its own ballast. There may be some exceptions to this, but I am unaware if any. Again, my MH knowledge is a little rusty.

how long do the bulbs last?

MH bulbs should be replaced once every 10-12 months.

whats the difference in euro made, german made, ect... bulbs?

Some people believe that German made bulbs are better than their Euro or American counterparts. This should be taken with a grain of salt. Kinda like the advocates for Fords versus Toyotas. I use Hamilton bulbs which are American made, and I love them.

would a 150 gal be better off with 2 x 400w or 3 x 250w? (the dimensions are 60x24x24)

I am not the person to answer this, so I will defer.

what else would i need besides the ballast, sockets, bulbs, and reflectors?

Other than a hood or pendant to put the bulb into, that is about it.

 

[reefrunner69]

what exactly does the different kelvin do?

Kelvin is a scale that determines what the color of th buld looks like. It is based on a candle, the higher the kelvin, the bluer the look. The more blue the more UV. The higher kelvin temps tend to make the corals more colorful, the colors are pigments developed by the corals to protect them from the increased UV, kinda like an SPF40 for the coral.

when setting them up, does each bulb run off of a different ballast?

In most cases yes, but there are dual ballasts. You'll just have to look into which is cheaper.

how long do the bulbs last?

Depends on who you ask and what depth tank they are going on, as a general rule, I like to change my bulbs at 12 or 13 months, but my last bulb was still going strong and the corals were still growing like weeds when I changed bulbs.

would a 150 gal be better off with 2 x 400w or 3 x 250w? (the dimensions are 60x24x24)

A 5ft 150, cool. I would probably do the 2 X 400w. I run a MH on a 30" tank and haven't had issues about the lighting, in the middle the light will overlap, the last few inches on the sides will be a little less intense, but I think it will work.

whats the difference in euro made, german made, ect... bulbs?

Where they are made, what ballast they need to run, powerconsumption color etc...

what else would i need besides the ballast, sockets, bulbs, and reflectors?

If your DIY, you'll probably need a power cord. Other than that...that is about it.

 

[BBReef]

Wow thanks for all the info and quick response.

 

[MadManMac]

Another very important MH issue is the ballast. There are two types, electronic and magnetic. The electronic is the more modern and usually preferred. Basically, an electronic ballast runs cool, uses less energy and is a lot smaller, whereas a magnetic ballast produces major heat, an audible buzzing noise and is usually quite large. Make sure to take this into account becasue many GIY magnetic ballasts are industrial grade and do not come with any type of housing to protect agaisnt heat. Look at HelloLights.com and AquariumLights.com for some different types and variations of ballasts and lamps. Good luck and let us know how it goes.

 

[reefrunner69]

Another very important MH issue is the ballast. There are two types, electronic and magnetic. The electronic is the more modern and usually preferred. Basically, an electronic ballast runs cool, uses less energy and is a lot smaller, whereas a magnetic ballast produces major heat, an audible buzzing noise and is usually quite large. Make sure to take this into account becasue many GIY magnetic ballasts are industrial grade and do not come with any type of housing to protect agaisnt heat. Look at HelloLights.com and AquariumLights.com for some different types and variations of ballasts and lamps. Good luck and let us know how it goes.

In addition to what was said here, electronic ballasts will also light all the bulbs, there are some mogul bulbs a magnetic ballast will not light because of the way it starts.

 

[BBReef]

With the 20 k bulb, is that enough blue to not have to add a lot of actinic? or would i still need a descent amount of actinic bulbs? is 10k the more commonly used bulb? thanks again for your help

 

[Biggen]

With the 20 k bulb, is that enough blue to not have to add a lot of actinic? or would i still need a descent amount of actinic bulbs

Depends on the bulb. I have Hamilton 20K's and they don't give me enough of the blue hue I expected them to give off. I am thinking about supplementing it with 03's.

is 10k the more commonly used bulb?

Hard to say. A lot of people use 6500K bulbs with 03's as well. In the end, I believe it simply comes down to personal preference. I really like a blue tank.

 

[reefrunner69]

Depends on the bulb.

I think it also depends on the wattage. I have not burned it in, and won't (gonna send it back) but the Coral Vue 20K was actually too blue for me, I have a pendant and have to run the actinics to run the fan in the pendant, with the actinics it was way too much. Without them it would have been about right with burn in.

Hard to say. A lot of people use 6500K bulbs with 03's as well. In the end, I believe it simply comes down to personal preference. I really like a blue tank.

Agreed, also, it depends on what your corals need, if you cannot produce the intensity needed for your corals at the higher kelvin temp, you'll need to move down in spectrum. It isn't just about spectrum, there is intensity to consider.

 

[BBReef]

I was looking some at ballasts, and came across probe start and pulse start. is this different than the electronic and magnetic? Whats the difference between the two?

 

[TheMadNucleus]

A few things to keep in mind:

This has been posted about 100 times on these forums:

Kelvin relates directly to the peak light wavelenght that a fully black object will emit when heated to that temperature not the spectrum the object produces when so heated. The spectrum will be more related to the object's molecular composition. While it is true that bulbs that are hotter (higher kelvin) lean toward the blue portion of the visible spectrum - that only applies for a limited section of the temperature range. In fact as the Kelvins go up the peak wavelenght cycles all through the spectrum in this order of wavelengths (ignoring wavelengths shorter than white) White, blue, violet, ultraviolet, Gamma rays etc. So it is not true to say that the higher the Kelvin the bluer the light because at some point it will become violet and then ultraviolet and then on past light radiation to very, very high frequency type radiation.

In fact 10,000 K bulbs produce a good deal of UV radiation and 20,000 K even more. There is a simple fomula for figuring out the peak wave length given Kelvin - I have posted it here a few times. A 20,000K bulb is actually going to be more violet than Blue when compared to the cooler 10,000k bulb

As for the actual color spectrum - this has more to do with a feature of artifitially created light called the CRI (color rendering index) where 100% is Mid-day sunlight.

 

[reefrunner69]

I believe it is either probe=magnetic and pulse = electronic, or they are both types of magnetic ballasts. Some bulbs require pulse start to fire. From everything I've read, electric ballasts will fire everyones bulb of the right wattage.

 

[BBReef]

One more question... can i put a 250w bulb in a 400w ballast? i want to get a MH for my tank, but am planning on upgrading in the future. it wont blow the bulb or anything will it?? thanks

 

[reefrunner69]

It won't work. You gotta use the properly sized ballast for the bulb.