Another question; is there anything special about the geisemann ballasts? I'm trying to decide between the geisemann nova pendant and the PFO with geisemann bulb.

BTW, on Sanjay's site it looks like the ushio 10k and the geisemann 13k bulb test out to almost identical color temp with the M80, around 10k. The XM 10k is quite a bit lower in temp. Go any higher, any of the 15k-20ks, and the PPFD plummets. Also, the ushio and the geisemann have a nice spike at right around 420 nm, where the 20ks all seem to spike at 440-450.