Quote Originally Posted by GarlicToast
The rumor is by having BOTH spectrums you are increasing potency...
The reason I'll run both bulbs (MH + HPS) during flowering, is...

HPS for flowering.
MH for vegetative.

Fine...

I'm thinking that during flowering, the plant will have what it needs from the HPS... but, if you add a MH, you'll help it in various other processes that it still runs. Even though it's flowering, it isn't like it "shuts off a switch" to the MH spectrums...

At least, those are my thoughts...