Intensity difference btw 400W and 250W DE

[Ger]

Does anybody know the light intensity difference btw. a 10K Ushio 400 Watt mogul style bulb and a 10K DE bulb? Assume both would use a reflector. I think there was a thread about that some time ago, but I can't find it.

[rbaker]

^

[dattack]

If only the 400 W DE were available.

[johnrags1234]

I personaly think that the 400w mogul is brighter.

John

[kbd]

400 W versus 250 W ?

I would have expected the latter to provide about 65 % of the total output of the former, maybe a touch more (the lower wattage bulbs will tend to be more efficient). Intensity will then depend on the size of the bulb and how it suits the reflector.

Why would you expect any different ? From you reference to other threads, you clearly believe that there might be another answer, and I'd be interested to see this as well. I find it a bit difficult to believe that electrode configuration would make that much difference, but I'm guessing here.

kim

[PetConnection]

They are very similiar...

250 HQI has higher peaks in it's spread of PAR, 400w has the PAR more spread out, with the peaks not as high.

If you have a good reflector these differences are less obvious. And by good I mean not the type that is open on both ends, as is commonly found on the 400w fixture "retro" kits. The HQI fixtures come with a nice closed reflector housing.

Read the articles and research that Sanjay Joshi has done on this subject.

[Ger]

I think you are right, it was the test done by Sanjay that showed similar intensities comparing certain 250W DE vs. 400W Mogul but that was primarily because of the reflector or lack thereof.
I have noticed a lot of German tanks using 250W bulbs (mostly BLV 10K) even on their deep tanks (over 30 inches deep). Is it possible that their 250W bulbs are more intense because of them running 220 Volts?

[dendronepthya]

I used to run 400W mogul socket bulbs and now I run 250W DE. On the 400W, I've used Iwasaki, some unknown 10K, and 12K sunbursts. The 250W was certainly brighter than the 12K's and seemed to be as bright as the other two. I don't quite remember the Iwasaki though since at that point it had been a few months.

I have a light meter now, so if I still had my 400W setups, I could tell you for sure which ones had a larger PPFD output, but I don't. Sorry. In the case that you have a Apogee PPFD (Quantum sensor), the reading I am getting from my 250W DE is around 1200 at 6" with reflector. Once the probe is submerged 6" into the water, the light drops all the way down to about 450 (which is still a heck of a lot).