[quote=LIP]
They each have to have separate ballasts unless you get a HPS or MH conversion bulb [Which ever applies]

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Or an electronic/digital ballast that automatically adjusts to either HPS or MH
slowthestone Reviewed by slowthestone on . Which light first? I'm looking at buying a light which comes with a red and blue bulb. Which bulb works best when? I mean do I use the red first or the blue? And why and which will work best at what stage of growth. Rating: 5