Difference between DE and Mogul based MH?

[BlueAbyss]

Hey everyone, I was wondering what everyone's experiences with Metal Halide lights are... Is there a difference between HQI and Mogul based bulbs, other than the glass envelope around the Mogul bulbs? I realize there must be a glass shield over the HQI bulbs to filter out UV, but is there a difference otherwise?

[Skimmerking]

i have read that the HQI is actually just a DE bulb. the HQI is the ballast type that runs it.

the Mogul bulbs do get air in the bulb when its made. the DE doesnt get any air due to it being vacum sealed the SE are not....

[BlueAbyss]

Hmm yes I knew this... actually, I think SE or mogul based bulbs are filled with an inert low expansion gas. I was just curious if one was different than the other, like if the light spread is different or what?

Upon further investigation, I think that a DE bulb (thanks asmodeus you got me thinking :lol: ) is actually the same as a SE bulb but without the glass envelope. So really, 2 bulbs made by the same manufacturer and with the same elements but one being SE and the other DE should put off the same quality of light.

HQI refers to how the bulb itself is built (Hydrargyrum Quartz Iodide). There are also HMI (Hydrargyrum Medium-arc Iodide) and other types of HID lighting systems, but they share the ballast and arc-tube design.

[Myka]

The main differences in performance between the bulbs are that the DE bulbs are more intense for the wattage, but spread their light over a smaller area. They also have more "hot spots". SE bulbs are less intense, but spread the light over a larger area, and have fewer hot spots. Many SE bulbs can be run on HQI ballasts which overdrives the bulb and actually makes the SE bulb more intense than the DE, however this wears the bulbs out a bit quicker, and you should consider replacing them every 8-10 months instead of the usual 12 months for MH bulbs that are operated normally.

Is that the answer you were looking for?

[BlueAbyss]

YES INDEED! That's exactly what I was looking for, thank you! I was looking at ballasts last night, and I'm thinking I'll get a HQI ballast and run a SE bulb, since I may end up with a 36" long tank in the end. I have no problem changing bulbs every 9 months, and I've heard of people having excellent results overdriving bulbs. Also that would give me the option to go to DE bulbs eventually if I decided I wanted to go that route.

My other option is to just buy a normal electronic ballast, because I think I would have some energy savings over the core and coil type HQI ballasts... unless I can find an electronic HQI ballast? I've never seen a ballast described that way, so I'm not sure if these exist.

Also, I'd like to find a 70W ballast if I stick with the 24" long tank, as I'd rather just run T5HO for the main light source in that case and have the MH as more of an accessory and for the ripple effect. 150W over a 20 gallon high seems like a lot, but maybe not since I do plan to have some SPS eventually. And definitely not too much if I do get the 36" tank.

[fkshiu]

There's no such thing as an "electronic HQI ballast". When dealing with MH ballasts there are four basic types:

1. Magnetic probe start (aka TAR or cap and coil)
2. Magnetic pulse start
3. HQI
4. Electronic

Generally speaking, you'll get the most PAR out of HQI ballasts but they will use a lot more energy at the same time. Electronics use less energy but put out a bit less PAR. Magnetics are in the middle usually. Electronics are smaller, lighter, make no noise and generate very little heat.

SE bulbs are pretty much jacketed DE bulbs. This allows SE bulbs to be run without a separate glass UV shield which DEs require. The shield can cut down on PAR.

Different bulbs may require different ballasts. For example, most European SE bulbs require a pulse start ballast because they have no internal ignitor. Electronic ballasts can run any bulb of the stated wattage.

Certain SE bulbs, like the Radium 20K 250w, are specifically designed to run on an HQI ballast. Therefore, you are not overdriving them at all on an HQI ballast and they will last a lot longer than 9 months.

A good resource to help you decide on your bulb/ballast combo is Sanjay Joshi's site:

http://www.manhattanreefs.com/lighting

[BlueAbyss]

Thanks for the help, I got it all figured out now.

One more thing, I've heard that different ballasts can make your lights seem more blue?

I'd like to avoid getting too blue, I'm sort of going for a crisp white but I've also heard that 10K bulbs are very yellow, though that may just have been in comparison to higher K bulbs. I understand how Kelvin ratings work, I just want to understand how I can keep my 10K (which should be blue enough for my taste since I'll be running T5HO supplemental lighting) from looking yellow. I want white, like BRIGHT WHITE.

[Myka]

The easiest way to get the whitest lights possible without risking too much money when you don't know the bulbs you like is to just go for a 10K MH bulb (which will be higher PAR than say a 15K anyway), and choose T5s to pull the light the way you want it. You do realise though, that your corals will look much nicer if you have a slight blue hue by using T5s with blue or actinic color? I have found that a blue or blue plus (blue + actinic) with a Fiji Purple (kinda reddish so it pulls away from the blue hue) for T5s REALLY makes the corals' colors pop. Really nice combination.

[mark]

Other consideration is the reflector height.

When making my canopy was looking for a low profile 250W pendant to fit inside, seemed the DE's where shallower than the SE's

[Tangman]

Other consideration is the reflector height.

When making my canopy was looking for a low profile 250W pendant to fit inside, seemed the DE's where shallower than the SE's
This is true and DE bulbs also run cooler than SE bulbs.

Also some SE end bulbs are specifically designed to run on HQI ballasts or electronic, check the bulb particulars, and will not ware out prematurely

[BlueAbyss]

Yes I'll be going with a 10K bulb, and using 'actinic' T5HO for the blue and general illumination. I've read good things about a couple 10K bulbs, hopefully the bulb and ballast combination I end up choosing doesn't push the bulb too yellow... from what I was reading, 10K bulbs often end up being more like 8K bulbs.

So, I'm getting a 175W electronic ballast, now I just need to figure out which one :lol:

[mark]

So, I'm getting a 175W electronic ballast, now I just need to figure out which one :lol:

do they even make 175W DE bulbs?

[BlueAbyss]

No, they don't, but electronic ballasts work with any bulb including 150W HQI bulbs.

[fkshiu]

If you want BRIGHT white and you're going with 175W electronics then the only bulb for you is the Iwasaki 15K. It is a true WHITE bulb with as much or more PAR than many 250W bulbs.

[BlueAbyss]

If you want BRIGHT white and you're going with 175W electronics then the only bulb for you is the Iwasaki 15K. It is a true WHITE bulb with as much or more PAR than many 250W bulbs.

Good to know, I'll now be going with the Iwasaki 15K bulb :biggrin: