If you're going to use T5s you should use an Icecap ballast and individual Icecap reflectors for each bulb. Also you want to use the GE starcoat mixed with some Geisman bulbs to ballance out how yellow the GE 6,500 k bulb is.
Most of the data that I've seen (PAR wise) was tested with overdriven bulbs (on an icecap ballast) and also using the icecap reflector. I don't know if the SLR reflector (I think that's what TEK uses) is the same I haven't seen them.
Lots of people get their T5 fixtures from
www.reefgeek.com I got mine from
www.diyreef.com they were very inexpensive and I mounted the endcaps to 1x3s from Home depot. You can make a box out of 1x6 and then nail the 1x3s to the top. This will give you a very inexpensive but good looking canopy. Plus by spacing the 1x3s out you'll allow the heat to disipate wich is SUPER IMPORTANT when using T5s.
The Grim Reefer and a few others have some EXTENSIVE info on T5s over on reefcentral.com and again all the data that they show is using a GE starcoat on an Icecap with an Icecap reflector. With that combination you get more par per watt then you do with Metal Halide. An icecap 660 running 4 54 Watt T5s (according to Grim) runs at about 303 Watts. The Par at 21 inches under that setup was better then with 250 watt MH bulbs. (I know it sounds like crazy talk) I have seen some other PAR readings using the Geisman Actinic Plus which puts out a very white light and also has very good par.
When people talk about T5 the above is what they mean, not a Nova fixture. I've also heard that Tek lights are the "true" T5s but I haven't seen any actual Par testing done with a Tek fixture. From what I understand they are fantastic fixtures but I haven't seen any data on what kind of Par they put out. You should keep that in mind when shopping for a T5 fixture (especially on e-bay). They are not all created alike. Most people like:
1 GE Starcoat 6,500 k
2 Geisman Actinic Plus 11,000 k
1 Geisman True Actinc (not even close to "true" but that's what they call it, PAR on this one sucks and it's just to balance color)
I personally find the above combo to be a little too blue. Tonight I'm going to try:
2 GE Starcoats
1 Actinic Plus
1 True Actinic
I'll let you know how it goes.
Oh i found a link showing the Par using different ballasts
http://reefcentral.com/forums/showthread.php?s=&threadid=724967&highlight=reflector