Single vs. Double ended bulbs...

[Reefer420]

Interesting- just found out the difference between HQI and Mogul bulbs (other than the double vs. single ended socket thing...)

Seems like Mogul bulbs have a UV coating on them - so UV glass is not needed. I called a light company about using tempered glass w/ a mogul bulb and was told that Light will not penetrate the glass b/c of the spectrum of the light and the UV coating. They suggested I use acrylic placed about 4" from the glass.

HQI on the other hand do not have that coating or whatever and are more intense - throwing off much more UV light. Tempered glass is needed b/c these bulbs burn hotter than single-ended, and the HQI light will penetrate the glass unlike the single ended.

They also said that many people prefer the light spectrum from a single-ended bulb to an HQI bulb- apparently b/c the technology for HQI is relatively new, the spectrum for the older, single ended bulbs are more precise and reliable.

 

[Deanos]

Did you call a light company that specializes in aquarium/reef lighting? :scratch:

 

[coralcrazy]

Um...DE..bulbs tend to last longer...then single ended..

 

[Reefer420]

yeah- I called aquariumlight.com (I'm probably going to get my retro kit from them so wanted to ask about the lighting...)

They recommended not to use tempered glass w/ mogul sockets b/c of the spectrum of the bulbs - no enough will get through...

but tempered glass is required w/ HQI bulbs...

I didn't know there was a differance before.

 

[Aqua Pro Builder]

They suggested I use acrylic placed about 4" from the glass.

I am confused here-4" from WHAT glass?

 

[Tonyscoots84]

from the bulb wingo... thats the glass he is talking about...

 

[Reefer420]

yup- they said that 4" from the single ended bulb ( as long as you use fans) was more than enough to not worry about melting...

HQI you cannot use acrylic...

 

[Reefer420]

OK- just found a posting on this on another forum ... FYI if anyone is interested, I didn't know that there was such a difference before..

..The two bulbs are very different.
SE bulbs are your "typical" MH bulbs and come with UV glass wrapped around the bulb.
HQI bulbs are a Mercury (Hg) Quartz Iodide bulb, and do not have any type of UV shielding. You must have UV glass between your tank and a DE bulb. HQI bulbs used with HQI ballasts will run at a much higher output than the equivalent bulb on a typical electronic or magnetic ballast. Only HQI bulbs can be "overdriven" like this. This all comes with a tradeoff though. Overdriving your bulb will increase the intensity, but may decrease bulb life.

And also saw this on ReefGeek.com

Experts typically recommend one metal halide lamp for every 2 feet of tank length and 150W HQI and 175W bulbs for tanks up to 24? tall, 250W bulbs for tanks 20-30? tall, and 250W HQI bulbs for tanks 20-36? tall and 400W bulbs for tanks 30-36? tall. By adding supplemental fluorescent lights to your metal halide system you can create a sunrise/sunset (dawn/dusk) effect.

Thought that was interesting info, me being new to MH lighting and all...

 

[alrha]

I prefer to have a protective sheild on my tank anyway (easier to clean a glass than to clean the entire inside of the fixture (reflector, bulbs, etc). I also think i remember reading that DE bulbs can penetrate deeper into the water. As such i have DE bulbs in my fixture - even though there is a smaller variety of bulbs (especially at the 400W range). - sort of like those who chose better but less popular macs over windows.

 

[Dace]

I prefer to have a protective sheild on my tank anyway (easier to clean a glass than to clean the entire inside of the fixture (reflector, bulbs, etc). I also think i remember reading that DE bulbs can penetrate deeper into the water. As such i have DE bulbs in my fixture - even though there is a smaller variety of bulbs (especially at the 400W range). - sort of like those who chose better but less popular macs over windows.

I thought that a de bulb has more intensity then a se bulb. for example a 250 de has then intensity of a 400 watt se. if true then using a 400 watt de bulb, wouldn't that be like have some Kentucky fried corals unless you have a minimum of a 30 gal tank.

 

[alrha]

my tank is a 187 gallon (30" deep) i actually have 3x400W bulbs on it, but being in the fixture with the protective glass and 2 smartfans (one on each end) my tank runs just fine without even a chiller. (my fixture is also from Cool Touch / AquariumLight.com)

 

[Reefer420]

I believe you are correct - the HQI is more intense than SE and also does not have the UV sheild in the glass.

 

[cali_reef]

http://www.reeflightinginfo.arvixe.com/

Here is Sanjay's web site with almost everything you ever want to or need to know about different MH bulbs and ballast. He did a lot of testing and is not influenced by an manufacture on these test results.

All I have to say is not every bulb and ballast are created equal, the blanket statement of 250W DE bulbs are brighter than 400W SE bulbs are not correct.

You should never us a MH directly over acrylic, it will craze and crack over time from the UV and heat. There is no need to have additional UV shield for SE\mogul based light bulbs, the glass on the bulb act as the shield. Adding more glass between light and the tank just cuts down the light and therefor a wasting electricity. Most(I stop looking at them) DE bulb fixtures have a glass shield to reduce the UV and keep the water splash off the bulb.

You will need a chiller if you are planning to run MH in our summer temperatures, unless you run the AC all the time to remove the humidity in the room and cooling the heat the MH puts out.

 

[cali_reef]

I believe you are correct - the HQI is more intense than SE and also does not have the UV sheild in the glass.

HQI describes a type of ballast, not the bulb style per se. Bulbs comes in two different forms\style, the SE(single ended, or mogul) and DE(double ended and no built in shield).