thats a nice ballast you got there.
you should check out sanjay joshis website where he evaluates many bulbs using that specific ballast.
I don't have a link handy, but I'm sure if you google "sanjay joshi 250 analysis" his site (I think it is either manhattanreefers or advanced aquarist) should coem up.
You'll take the guesswork right out of it.
I am looking for those exact ballasts for my 250 phoenix 14k bulbs.
Best par for a 14k (or near best) and very nice blue and actually very well rated on your new ballast by Sanjay.
edit - found the link.
http://www.advancedaquarist.com/2005...t=Sanjay+Joshi