Quote Originally Posted by Purple Daddy
Look for lumens vs wattage, the most lumens for the least wattage is your most economical way to go.
By that logic everyone should buy low pressure sodium lights at 200+ lumens per watt versus the best HPS 150 or so.

But it doesn't work out like that, because LPS is almost pure orange/green and IR, and is in fact horrible for plants.

Lux won't help you out until you see some spectral output charts, then you can make meaningful comparisons and come to an informed decision, with our help.

Also, how big of an area are we talking about?