You can finish them with a MH like tiki said.. What type of ballast do you have? Is it a magnetic ballast? HPS or MH? Switchable? I might can tell ya what may be wrong,with knowing a few things..:thumbsup:

May not be your lamp...
GaGrown Reviewed by GaGrown on . weak hps lamp hi all, i'm in the start of the 7th wk of flowering. my light came on tonight but it's like half power, it isn'nt bright at all, very weak. can't afford another hps lamp right now. my ? is can i finish these plants with a mh lamp? Rating: 5