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jpc763
09/17/2008, 04:19 PM
First I read the FAQ (well the first page of each) and still have questions.

I got a single 250w Metal Halide retro system and had some questions.

Basics: Mogul base, retro reflector, non-discript balast.

First is the balast. I am not sure if it is magnetic, electronic, whatever. How do I tell?

Second is the bulb. Seller told me that the bulb is "basically new". How do I tell if a bulb is new or not?

Third is the bulb again. It is a 10k bulb which is the same color as my T5 bulbs so I figure I should get a different color. What color? I looked at 14K and 20K online. What is the difference? Why one over the other?

Sorry for the newbie questions, but I have no clue about MH!

grigsy
09/17/2008, 05:18 PM
As far as the ballast goes, if there is no indication, the weight should give you a clue. The magnetic 250 watt M58 ballast generally is about 12 - 15 lbs. The M80 HQI 250 watt ballast is generally about 18-20 lbs. An electronic ballast will be much lighter - sometimes only maybe 4-5 pounds. You could always open it up the enclosure and check inside. The magnetic M58 ballast will have a transformer and a capacitor. The HQI ballast will be transformer, capacitor and starter. The electronic will just be one electronic ballast only.

As for bulb, that can be tougher. Most bulbs, even one that are burned for a few hours will have a dark spot on the inner arc chamber. That is the gas which has adhered to the bulb once it has been burned. If there is no spot, it is likely brand new. Most new 10K bulb burned in for 100 hours will generally appear as a white color.

If you have a 10K halide bulb now, you may want to change the T5 bulbs to actinic blue. That may be cheaper than switching the halide bulb to a different Kelvin. If you would rather change the halide bulb, try a 14K bulb. Those are a nice color.

mat167
09/17/2008, 05:41 PM
Just to add on to what grigsy said...
The higher the Kelvin rating, generally the more blue the light will appear. That means that the 20 000k bulb will have a distinctive blue colour, and personally isn't my favorite. The 14 000k bulb is more of a mix of the 10 000k and 20 000k, so it looks really bright and has just a tint of blue. I much prefer this bulb because it looks fine all by itself or you can supplement it with fluorescent bulbs. For the most part, the colour of the bulb is for aesthetics, but it's the concensus among aquarists that a bluer light will cause stony corals to show a better colour, and a whiter light will result in faster growth. I'm still reasonably new to the hobby myself, so as much as I would love to go into a whole speech I'm sure I would say something misleading (if I haven't already, though I'm confidant in my information). If you're serious about lighting, there are copious amounts of information on the subject regarding wattage, lux, kelvin, anything else you can think of and more.
The best thing is to get a look at as many systems as you can so you can judge what looks best.
Good luck

jpc763
09/17/2008, 06:43 PM
<a href=showthread.php?s=&postid=13373079#post13373079 target=_blank>Originally posted</a> by grigsy
As far as the ballast goes, if there is no indication, the weight should give you a clue. The magnetic 250 watt M58 ballast generally is about 12 - 15 lbs. The M80 HQI 250 watt ballast is generally about 18-20 lbs. An electronic ballast will be much lighter - sometimes only maybe 4-5 pounds. You could always open it up the enclosure and check inside. The magnetic M58 ballast will have a transformer and a capacitor. The HQI ballast will be transformer, capacitor and starter. The electronic will just be one electronic ballast only.

As for bulb, that can be tougher. Most bulbs, even one that are burned for a few hours will have a dark spot on the inner arc chamber. That is the gas which has adhered to the bulb once it has been burned. If there is no spot, it is likely brand new. Most new 10K bulb burned in for 100 hours will generally appear as a white color.

If you have a 10K halide bulb now, you may want to change the T5 bulbs to actinic blue. That may be cheaper than switching the halide bulb to a different Kelvin. If you would rather change the halide bulb, try a 14K bulb. Those are a nice color.
<a href=showthread.php?s=&postid=13373227#post13373227 target=_blank>Originally posted</a> by mat167
Just to add on to what grigsy said...
The higher the Kelvin rating, generally the more blue the light will appear. That means that the 20 000k bulb will have a distinctive blue colour, and personally isn't my favorite. The 14 000k bulb is more of a mix of the 10 000k and 20 000k, so it looks really bright and has just a tint of blue. I much prefer this bulb because it looks fine all by itself or you can supplement it with fluorescent bulbs. For the most part, the colour of the bulb is for aesthetics, but it's the concensus among aquarists that a bluer light will cause stony corals to show a better colour, and a whiter light will result in faster growth. I'm still reasonably new to the hobby myself, so as much as I would love to go into a whole speech I'm sure I would say something misleading (if I haven't already, though I'm confidant in my information). If you're serious about lighting, there are copious amounts of information on the subject regarding wattage, lux, kelvin, anything else you can think of and more.
The best thing is to get a look at as many systems as you can so you can judge what looks best.
Good luck

Thanks Guys! Actually 2 of my T5 bulbs are Actinic and 2 are 10K. Based on the weight, I think the Balast is M58. Is that pulse start or a probe start?

jpc763
09/17/2008, 09:06 PM
Well I opened up the housing and found that it is in fact a M58 balast manufactured by Advance. Hellolights.com has it here

http://www.hellolights.com/index.asp?PageAction=VIEWPROD&ProdID=174

It is a pulse start so I need to make sure that I get a bulb that is pulse start.

Thanks again!