Well, I'm sure someone is going to mention this and in clearer terms, but by HALIDE...do you mean Metal Halide? That is fine for Vegging. BUT, if you meant HALOGEN, then crazywill is right...they are useless.

3 weeks and only 1.5 inches??? Something is wrong. Sorry I cant be more help. Just not enough time to type. Someone will answer any other questions you have. Good luck!

TGF