Recently I purchased a 150w metal halide bulb from aquatraders. Initially I am very pleased with the fixture itself (doesn't run as hot as the older ones used to) however I am looking to upgrade the stock bulb to a 20k 150w hqi. Has anyone had this fixture and upgraded to a 20k, if so, what bulb did you use? I have seen some pics of these with the phoenix 14k with pretty good results, however I would like to shoot for 20k.