You can if you have one of the switchable ballast

Mh use only a transformer and capacitor

HPS light need transformer (w/ extra 277v tap). a capacitor and igniter to make the light work.

You can buy conversion bulbs, but they are expensive.

You can also just buy a HPS light and a Hortilux bulb and use it start to finish (once the plant reaches the vegetation cycle anyway)

You should still use fluorescent lights for clones and seedlings.
Zandor Reviewed by Zandor on . Light Question What is the deal between the the hps and mh light systems? Can't you just use the same ballast and fixture, and swith the bulbs? Rating: 5