double ended mh bulbs vs screw in type

[robzilla]

hi, whats the difference with the double ended bulbs and screw in type.
a guy at j&l suggested a double ended unit but warned me that they dont stock too many bulbs.
is there benefits of double ended?

thanks for the help

[Nemo]

I am told the double ended ones put off a lot more light than the single ended ones

[mr_alberta]

Usually the DE bulbs seem to give off brighter or more light because the reflectors designed for them are much more efficient at reflecting the light back into the tank than most reflectors made for single ended bulbs.

[StirCrazy]

Originally Posted by BIGDADDY_23

I am told the double ended ones put off a lot more light than the single ended ones

nope they don't. a DE actually puts out less light over the same area but because of the size they can have reflectors that are designed to concentrate the light over a smaller area giving the appearance of more light.

If you are stuck for room they are the ones to use. but you can buy the HQI ballasts and drive the screw in ones also as I do. this way if you go 250 watt you can run any screw in bulb out there that is 250 watt on a HQI ballast.

Steve

[BrainVat]

For the same brand of bulb, HQI does put out more light per watt, and conversely generates less heat per watt. I've been told that this is a feature of bulb design, and has to do with the fact that current passes over the bulb coils in a single direction without having to be looped back like in a mogul. The end result is less resistance at the bulb and higher output.

To look at a "real" scenario, compare the XM 20k double ended vs 20k mogul bulbs. Using the same HQI ballast, the DE bulb generates more light. This demonstrates that the increase in intensity is a function of the bulb, not the ballast.

link


(sorry for the long link)

Edit: I have modified the link so that it shows up as smaller. If you click on it, it is the same URL, but this way it doesn't bugger up the thread width. -Tony

[Samw]

Um, in that link, the SE bulb had the higher PPFD with 79 while the DE bulb had only 55. Doesn't that mean the SE bulb has more light in whatever test that was?

[Samw]

Its a myth that DE lamps produce more light than SE lamps.

"Comparing the data here and other 250W DE articles with the data for 250W Mogul lamps, should provide enough factual information to dispel the myth that 250W DE lamps produce more light output than the 250W single ended mogul lamps. A general sweeping statement to this effect cannot be made, and depends on the lamp under consideration"

http://www.advancedaquarist.com/issu...04/reviewb.htm

[Samw]

One thing I do notice is that my arm use to get red from working on my tank when I had my DE fixture. Now, that I switched to a SE setup, I don't get these sunburns anymore after working under the light for hours.
My DE sytem might have been giving off more UV (even though there was a glass shield).

[StirCrazy]

Originally Posted by BrainVat

For the same brand of bulb, HQI does put out more light per watt, and conversely generates less heat per watt. I've been told that this is a feature of bulb design, and has to do with the fact that current passes over the bulb coils in a single direction without having to be looped back like in a mogul. The end result is less resistance at the bulb and higher output.

Sorry you were lied to. I though that also but then I tested the output of my HQI driven SE 10000K AB set up against Sams HQI DE 10000K AB and even with the reflectors on I got a higher PAR output from my set up, this got me thinking.

Steve

[Bob I]

Something is spreading this thread way out wide making it hard to read.

I am upgrading a 175W single ended to 250W, and was thinking of getting an HQI pendant to replace the SE pendant, but if there is no advantage would I just get a new ballast and bulb. It would be about $300.00 less expensive.