Is anyone using the T25, does it have any advantages over the T15 that are worth the price in heat and wattage?

T25 (and T15 for that matter) is mearly a lamp envelope shape. The only disadvantage to using a T25 would be that the shell is larger than a T15, which means you have less options has far as a reflector is concerned. Is there a particular lamp you are interested in using ? If so, it would be best to post a link to the lamp, or at the very least some specifications. The heat and wattage will be determined by the actual lamp selected, not the shape of the lamp (ie. T15 or T25).

gs

oops, what i meant was the 1000w t25 model that USHIO sells

according to their spec sheet, 1000w MH bulbs come in t25 form.

http://www.ushio.com/files/catalog/pav-met...earch=%22t25%22

In addition to the size of the outer shell limiting the reflectors you can use, the major problem with these types of 1000W lamps is the arc size. These arcs are simply too large to fit through the triplet, which just leads to a lot more heat without any real benefit of the projection being brighter. Will a 1000W lamp like that one be brighter than a 400W lamp ? yes, most likely it will. Will it be 2.5x as bright. No. Will you need to do some major control of the heat given off by a 1000W lamp. Yes. You would be much better off going with a 575W HMI type lamp that has been used around here recently... either that or do something like Arizonavideo... he did a 1200W lamp, but it's a short arc lamp like the HMI style.

Also. I noticed the link to provided indicated 1000W T25 lamps, but they are colored style lamps. You'd be looking for something different than that; something with a better spectrum of light, closer to that of sunlight, or the D65 standard.

HTH.
gs

thanks for the awesome info, I saw the double ended 575w variety have amazing arc lengths but super short run times, i guess I will stick with what we know to be best ... the ll65k.