Which bulb do I use

[D.A.A.S.69]

Like kingfish said, use MetalHalide till about a week or two after seeing pistils, then put the Hps, lamp-bulb in.
Ps- some people put the MH, back in the last couple of weeks before harvest, ,supposedly for trich production.
Good luck, HappyGrowing

[Redwasp]

Start MH. About day 40 or so switch to HPS. Well when the buds are forming nicely on all plants. Could be day 40 could be earlier or later. But the answer is honestly that both will make nice plants.

[Toker1]

Prior to my time... all flowering was done using MH. The answer is both will get the job done. HPS is known to make plants stretch but will end in heavier yields. MH will yield lighter, but the blue spectrum will bring out those trics.
Personally, I use MH until the first 2-3 weeks of flower. Keeps the stretch minimal. Then I switch to HPS until the last 2 weeks of flower when I switch back to MH (for increased tric production).

[FlowerPower]

Hi

I have grown photoperoid seeds many times, but this time my seed supplier gave me 5 auto flower northern lights female seeds. I would like to try going an auto flower but do I use 600W metalhalide or a 600Watt high pressure sodium. I could not find the answer on your site.
Thanks
Flowerpower