How To Use Progressive Web App aka PWA On 420 Magazine Forum
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QUICK ANSWER IS YES, HPS Will work. I DON'T THINK IT'S GOOD FOR THE WHOLE GROW ROOM. If you have the HPS you're half way there so don't give up. I would use the BLUE fluorescents to start your future plants too. After they've had a good start you can move them under a MH for your Veg and later to an HPS for your flowering. If you don't have (or want to spend) the extra CASH on an MH system then your going to need FLUORESCENT TUBES to replace the Metal Halide (MH).
I would go with 8 of the 4'ers at 40 Watts each tube. DO NOT USE ANYTHING WITH DELUXE IN THE NAME.
If you want your BLUE then look for "COOL WHITE" and "DAYLIGHT." If later you also want to add RED then look for "SOFT WHITE" and "WARM WHITE." Remember not to use Deluxe. Cool White emits 50% more light then the Cool White Deluxe.
Now when you get that 400 watt HPS set up you're going to have to think about cooling??? If you're in a 10' x 10' room it shouldn't be a prob. If you're in a closet you're going to have issues.