you can use a 400 watt hid light. You will want one that is air cooled because it will produce a lot of heat. The t-5's are florescent lights. They come in 2' and 4' sizes. You can get them with as many as 8 bulbs, unlike the hid light which has one bulb. With the hid you would need a switchable ballast if you wanted to use both the mh (metal Halide) and the hps (high pressure sodium), or two separete ballasts. With the t-5, all of the spectrums of bulbs fit the fixture, no seperate ballast is needed. Because you are spreading the heat over a two foot or four foot fixture you have less heat to deal with, you would not need to air cool the light and it will take up a foot less height. The ballasts are in the fixture instead of being seperete. The 4'- 8 tube fixture uses 440 watts of electricity and will put out light equivalent to a 600 watt hid. By the time you add the cost of running a fan to cool the 400 watt hid, the electric costs will be about the same, but you will have more usable light. I don't own stock in any light company. This is just scientific advancement in light fixtures. Folk look at the hid's and the are bright so they assume its more light and it maybe. Problem is you have a lot of heat and can't get them as close to the plants. The light is lost as far as the plants are concerned.
I started with 3-400 watt hid's, still have one in use which I will replace with a t-5 fixture. If I were growing in a closet, I'm not, I would get the t-5's not the hid's. VV