HPS vs MH ! HPS overrated ???

HPS has a higher lumen count, that's why they're preferred for flowering.

Metal Halides produce more light in the blue side of the spectrum which is ideal for the veg phase.(root, stem, and leaf growth.) but HPS produce more yellow/orange (and some red light) which is necessary for bud growth on a flowering plant.

If you have the choice between two of equal wattage the HPS is the better choice as it produces more lumens per watt. Buds grown solely under MH lights will be airy and loose.

Here's a chart of relative lumen-to-watt output to help.

Incandescent("grow lights"): 17lumens/watt
Mercury Vapor: 45-50lumens/watt
florescent: 60-70lumens/watt
metal halide: 90 lumens/watt
High Pressure Sodium: 107 lumens/watt

Originally Posted by straitkilla911

Metal Halides produce more light in the blue side of the spectrum which is ideal for the veg phase.(root, stem, and leaf growth.) but HPS produce more yellow/orange (and some red light) which is necessary for bud growth on a flowering plant.

Did you look at the graphs I attached?

Found this chart which was slightly easier for me to read:

MH


HPS


So although the two HID lamps share a similar spectrum range, The Metal Halide still fails to produce the amount of yellow/orange/red light the HPS does as well as a lower lumen-watt ratio

I strongly disagree that MH lights produce airy buds. That's absolutely not the case. A lot of growers are moving to MH only because they produce tighter, denser, nugs. The complaint most people have against MH is that the buds have too much leaf material. I haven't found that to be the case, although I've tried flowering under CMH instead of MH.

A grower shouldn't make all their decisions on lumens, as that is a measurement for humans, not plants. You could have a 1,000,000W bulb in the wrong spectrum and it would not work.

I suggest trying the CMH bulbs although they max out at 400. I'm did a CMH+HPS veg and now flower and I think its the best combo overall.

Originally Posted by straitkilla911

So although the two HID lamps share a similar spectrum range, The Metal Halide still fails to produce the amount of yellow/orange/red light the HPS does as well as a lower lumen-watt ratio

1. I agree with you on the lower lumen-watt ratio, making HPS setups a little more efficient in that aspect.
2. The charts I attached and the ones you attached seem to contradict each other. MH seems to produce more oranges than HPS in my charts. But then again, the Y axis scale wasn't specified...

one more I found on the web: pretty interesting

Spectral_Properties.jpg

Yes it would appear as if they all seem to contradict each other. anyone have a truly accurate chart comparing HID lights of the same wattage .