I would love to be able to set up a nice comparitive study and present some publishable data describing the PAR of various T-12 avalible, but right now I don't foresee that happening. I did this comparison a few months ago and don't have all, or the exact, values infront of me. But if memory serves me correctly the GE Plant and Aquarium bulb was producing about 30 umol/m2/s (incase anyone is wondering, PAR is measured as the number of photosyntheticly active photons striking a unit area over some period time, that is why it is given in umol/m2/s). ESU's UVB and UVA (Desert Sun Bulb, I belive), along with a soft white bulb (I belive by Phillips), a Sunlight bulb (can't rember the exact name, but it comes in a yellow and orange package), and the standard Cool White by Sylvania (along with a few other bulbs I can't think of) were all pretty similar, producing between 50 and 70 umol/m2/s. The F40SP65 was producing around 100 umol/m2/s. Like I said before all the bulbs were the same age, but they were not right out of the box. So do not take these values as word of god as to what the bulb will do, just something to compare between bulbs (obviously a newer or older bulb will behave diferently).
Tony I think you are still a little confused as to what color temp is. I had the same conceptual problems with it for the longest time. Trying to reconsile it being the color of the bulb, but not the "color" of light it produces (ie the spectrum). Even though there may be some lose correlate between the two, it is a common pitfall to think the color temp describes the spectral out put.
Good call on looking up the price. I should have included that. The bulb is difficult to come by where I am at (Gainesville FL), where the only way I found to get them localy is to purchase a case of 30 (not going to happen). But every where else I have lived I have had no problem finding them.
Enjoyed the conversation Tony,
Jay