MH bulbs PAR readings

[George]

I got a MH fixture from EBay the other day (in this thread). I would like to know if the MH bulbs (15K, 250W) come with the fixture are any good. They look white but what are the PAR of these bulbs. This is a little experiment I did to compare XM bulb running on my other tank with ebay bulb.

Setup
XM bulb set up: PFO probe start MH ballast 250W (M58), XM 10K 250W SE, unkown reflector (read: inefficient). Bulb is 3 month old.
Ebay bulb set up: Ebay 250W electronic ballast (seems to be icecap clone), ebay 15K 250W DE bulb, stock reflector in fixture, glass shield below bulb. Brand new bulb.

Equipment
I built my quantum meter from a apogee SQ-120 light sensor connecting to a Fluke 7 multimeter.

Testing method
Turn on MH, wait for 30 minutes before measuring. Place sensor 6" directly under a bulb, and above water.

Results:
XM bulb: 1600
Ebay bulb: 1450

Summary
At first glance, ebay bulb is comparable to XM bulb in term of PAR. XM bulb is 3 month old and may loose a little bit of PAR but ebay bulb is behind a glass shield.
This is the first time I use ebay bulb. I heard that they can loose PAR and shift spectrum quickly. I will have to re-test them after 3 months. This is a very quick and dirty test. I don't want everyone rushing out and buying ebay bulbs and all your corals turn brown. Do your own DD (due diligent).