Your MH ballast does not have the required ignator to make the HPS light up. You can purchase a conversion bulb that work with your ballast. http://www.discount-hydro.com/lightbulbs.asp I think it cost 75.00.

Peace
Zandor Reviewed by Zandor on . Harvest Time and MH Question HI, i plan to harvest next week and i read somewhere that when i cut my plants i am suppose to hang them upside down. But i don't know for how long. Can someone tell me the best productive procedure. Thanks Next the MH question. Since i am such a cheap bastard i have purchased a 175 MH light (ideal for my setup) and i have a HPS bulb. When it is time to flower can i put the HPS bulb in the MH light fixture. Bulb HPS 150 watts. I'm trying to not have to get a separate Hps light system. Hope Rating: 5