What's the best K for MH light in vegetative growth?

Hi Everyone!

Nube grower here. I've just started my first grow project in a 2.5x4 Ft closet. Got a switchable MH/HPS 400 W ballast. Want to use MH for the vegetative phase and HPS for flowering.

I read that phosynthesis requires light of 420 nm. So I am thinking anylight that focuses on that blue wavelength may give the most efficient output for photosynthesis and grwoth like a 6000K or higher MH. The bulb that came with my setup however is a 4000K bulb which seems to have more yellow and red 500-650 nm. I am wondering if this may be actually a bad selection for the vegging phase and I should go and get a 6000K MH bulb instead. I would appreciate any insight on this matter.

Cheers!

That 4000k bulb is the hps bulb that you use for flowering. Get a 10000k mh bulb for veg.

Woah there...10000K?

the 4K lamp is probably a standard MH lamp, freak.

You are probably looking for/at a Daylight Hortilux lamp if you want 6500 K///or there's an Iwasaki lamp out there that is also very high K for veg. A lot of folks use the 6500K MH for buddin too..it replicates sunlight very closely on the graphs...etc.

FWIW..as an average gauge...A hortiluxs Enhanced hps is 2150K... a warm deluxe hps/Agrosun MH is 3000K a standard MH is 4000K...the daylights, either a Cool Deluxe by Sunmaster or a horti Daylight are 5600-6500K respectively.

hope that helps

bt dt

Thanks BT DT!

Yes you're right it is a 4000K standard MH buld. So you agree with my perception that I should go higher to around 6000K.How is this one on ebay:
eBay: 400 watt MH Metal Halide Grow Light Bulb 400w BLUE spec (item 180130491941 end time Jul-08-07 21:15:00 PDT)

go for the least expensive mh bulb with the most lumens.

4000k?? You will have some slowth growth there buddy. 6500k is best, You can get a way with 6000-7000k.

Wow after Installing the 6500K light I could see the big growth difference!

Thanks all for the suggestions!

What did the upgraded bulb run you?

I decided to go with a known brand Agrosun which was twice as expensive as the no name brand I found on Ebay. So I paid $59 for the 400W 6500K 36000 lumens MH bulb.

Peace