HPS bulbs are the most common HID to use, especially during flowering, giving off characteristic reddish light. The red in the light spectrum encourages good flower/ fruit growth. It is possible to use HPS during vegetative growth, but only for a week or two. Older plants start to look a little unnatural and 'lanky', with large internodal length and brittle stems. For this reason conversion bulbs, or enhanced spectrum bulbs are needed, or even better, a Metal Halide. HPS bulbs can be re-started after about 3 minutes if powered down
Sunmaster Lamps are very similar to Grolux lamps in that they too have been specifically developed for indoor plant growing and are spectrum adjusted to perform well in both vegetative and flowering growth. They are a great option for anyone looking to experiment with different lamps as you may find that the exact spectrum offered by one lamp may suit your plants better than another.