metal halide from hellolights

[tubbanorman]

I am thinking about getting the 400w magnetic retro kit from hellolights to add to my 55gal. I want this one so I can use it when I switch over my 120, so I can add another 400w later. I haven't used MH before and I was wondering if anyone has used this ballast? the link is below.
When I do make the hood with the MH bulbs do they need to be separated from the top of the tank by glass, incase of water splatter? It seems like a good deal at $137 with an Iwasaki 6500k bulb. Is this an ok bulb?

http://www.hellolights.com/40methalretk.html

 

[gcvt]

I haven't used that kit so I can't comment on its components.

It would be advisable to have something in place to keep splashing water from reaching the bulb(s). What's in the tank? Any big splashers?

The bulb type depends on the look you're going for. The 6500k bulb will look somewhat yellow-ish, the 10,000k bulb will look more white, and the 20,000k bulb will look blue-ish. I'm still researching MH for my 100g and I don't think I'll be using any bulbs below 10,000k. Just personal preference.

 

[tubbanorman]

Thanks, I may have to spend a bit more on the bulbs then. I don't like the yellow look, makes it look like a fresh water tank.
I don't have anything in the tank that will make waves, it's all small fish. The largest is a Lawnmower, but I wouldn't want the bulbs to break.

 

[slipknottin]

$137?

The ballast costs $50, the bulb costs $60 and the mounting socket and bracket cost $10.

The only bulbs that ballast will run correctly are the Coralife bulbs. You want a pulse start ballast for the radiums, ushios, and AB bulbs. The pulse start ballast only costs $65

 

[Alastair]

As far as the bulbs are concerned, I don't think that 6500K's would seem too yellow. Color temperature can be a bit confusing, but sunlight falls around 5000K. Any bulb with a number lower than that is redder than sunlight, and any bulb with a higher number is bluer. So a 6500K is actually bluer than a freshwater tank, which usually use around a 4000K bulb. 6500K is only yellow in contrast to 10000K or 20000K units.

A more important factor is what kind of animals you want to keep. Animals from shallow water will *mostly* prefer lower kelvin ratings and higher wattages, whereas animals from deeper water will prefer higher kelvin ratings and lower wattages.

Most ballasts differ very little in terms of performance for various bulbs, as long as they match the general bulb type. There are slight differences, and certain bulbs will definitely perform better with certain ballasts, but the difference is seldom enough to worry about. If seriously in doubt, find out from the manufacturer of the specific bulb exactly what you need. And always choose the bulb first, in light of what kind of animals you want to keep.

--Alastair

 

[slipknottin]

Originally posted by Alastair
As far as the bulbs are concerned, I don't think that 6500K's would seem too yellow. Color temperature can be a bit confusing, but sunlight falls around 5000K. Any bulb with a number lower than that is redder than sunlight, and any bulb with a higher number is bluer. So a 6500K is actually bluer than a freshwater tank, which usually use around a 4000K bulb. 6500K is only yellow in contrast to 10000K or 20000K units.

compared to 20K or even 10K bulbs they are noticable yellow.

A more important factor is what kind of animals you want to keep. Animals from shallow water will *mostly* prefer lower kelvin ratings and higher wattages, whereas animals from deeper water will prefer higher kelvin ratings and lower wattages.

All corals will grow better under blue light than under white light. There coloration will usually also be more intense under blue light. Wattage is a much more important factor than color temp is.

Most ballasts differ very little in terms of performance for various bulbs, as long as they match the general bulb type. There are slight differences, and certain bulbs will definitely perform better with certain ballasts, but the difference is seldom enough to worry about. If seriously in doubt, find out from the manufacturer of the specific bulb exactly what you need.

ballasts make a huge difference on both the life of the bulb, the color of the bulb, and how much light it emits.

Simple case... the 20K Radium bulbs. On a standard MH ballast they will often fail to start, and will look quite blue. On an HQI ballast they will always start and look much whiter, but often results in premature bulb failure. On a pulse start ballast they will light perfectly, and the bulb will look as its supposed to and last over 8 months.

 

[Alastair]

Sorry, Slipknottin, I have to disagree with you on this one. It is true that Radium bulbs will not operate correctly on standard can-and-coil ballasts, but, they are something of a special case and there is a reason for that. Radiums are a German made bulb designed for ballasts operating on European input voltages and a 50hz cycle as opposed to US voltages and 60hz cycles. The pulse-start ballast helps overcome these differences, but most widely available bulbs do not have this limitation. I've seen several studies on the differences between different halides on different bulbs, and in most cases the percentage differences on light output vs power consumption are in the single digits. There is no question that Radium's are excellent bulbs, but they are not the only bulb choice, and they are expensive for someone working on a budget system.

Nor do I agree that a bluer bulb is necessarily better for coral growth. The blue bulbs are excellent for color rendition, true, but IME they do not have a significant effect on growth. From the standpoint of wild corals - and most still are - SPS corals will typically be adapted to a color temp in the range of 6500K to 10,000K; Softs and LPS from slightly deeper water will be adapted to light in the bluer range (10,000K plus). That's simply a factor of how water transmits light and the respective depths at which things grow, hence my comment that the type of bulb to choose will depend a little on what kind of animals you want to keep. I didn't mean to suggest that wattage isn't important, but normally you can choose a variety of wattages within each color temperature range, so you have more flexibility to work around wattage needs.

--Alastair

 

[slipknottin]

I gave one example. There are numerous others. How about the most common 6500K Iwasaki bulb? It uses more electricity, has less output, and looks yellower on a MH ballast. It should be run on a MV ballast.

AB, radium, and ushio bulbs should all be run on pulse start ballasts for maximum effectivness.

Photosynthesis (and calcification in corals) is affected primarily by light in the blue range, and secondly in the white range (Kinzie 1984)

Your argument about corals at the surface getting 6500K and corals in deeper water getting 20K light doesnt seem contrary at all to my statement. The corals at the surface will be getting more blue and white light than corals deeper under water. The fact that corals can live in deeper water where there only getting 20K light seems to illustrate the point.