Which one should I choose?

I found a light system that has a 400watt HPS and 400watt MH together. Now should I buy this system or buy a 600W Hps for my flowering cab? For the money it cost the same as buying the 600 watter.:S5:

I'd say that mostly depends on heat issues. What size is your cab? 800W might be a lot for a small cab.

well im assuming you can light either the mh or the hps, or both at the same time. i would be weary of that fact. if they both come on it may be a heat issue if they can be switched on and off seperatly i would get the mh and hps, becuase u cover both vegg and flowering. and 400wtts is mucho for a cab. also if this is just for flowering, the mh is completely uneccessary, and a 400wtt hps alone may be enough.

Unless you have glass blocking them you can use the UVB rays and blue light from the MH, if there aren't heat issues with that. You would have some very nice buds.

I have a Sunlight 600w HPS + 400w MH under one reflector. The ballast electronics are in one metal box. I like the idea of a 'blended' light spectrum but honestly there is no big difference in growth/yield (that I can see) when compared to say running a 1000w HPS.
To answer your question : If you're also intending to veg. then go for the 'blended' system; if only for flowering then go for the 600w HPS.

So since i am going to use this space for flowering I should just get a 600W digital HPS ballast and light? This would be the best bet huh?

if its just for flowering i would use the extra watts used in the mh for more hps.