Hello Speedking I use the ballast, tranformer thing that takes both and yes it is worth it

The MH bulb provides light from the blue end of the spectrum which is ideal for vegitive growth.
The HPS bulb provides light from the red end of the spectrum which is ideal for the flowering.


However if I was just going to use one only, personally I would choose the MH bulb as it also does produce enough red light to induce flowering.
Altohugh a combination of the two is by far the best bet


love mand xxx




Oh mine is a 400 watt set up and seems to cover my 36 sq ft grow area just right