Hudson, are you positive about this? I've talked to many individuals (on this forum and otherwise) and I've been told the 250w would be sufficient. I, for one, don't know all that much so I must inquire....
I have a couple questions for you though hudson if you don't mind.

- I plan on getting a remote ballast system but ventilation is going to be a problem! How hot would a 400w get compared to a 250w? I'm certainly going to have ventilation and sufficient air circulation but I can see that venting OUT is going to be an issue. So, do you know the average operating temperatures of each? Does anyoen know for that matter?