Agreed. If we're talking about different types of lights the wattages get confusing. The blurple mfrs make it worse with their "equivalent" or "replaces" wattage. We all know that is crap. In any case, I was just talking about the high quality, full-spectrum lights. In other words, Samsung LM561c, LM301b, or some equivalent diodes. When you're talking about the same diodes a wattage/sf does make a decent proxy for PAR levels.
It's common opinion from a lot of growers that 30w/sf of good LED or 50w/sf of HPS or blurples is a good rule of thumb for flowering, but maybe that is high. You seem to be getting real good results, and, if you're pulling 520w at the wall, you're probably only getting about 475 watts at the boards depending on your driver efficiency. That's only about 20w/sf. Good for you. Your system must be dialed in tight. I do wonder if a bit more light would push things over the top for you, though. With the LED prices having fallen like they have it might be worth a try. If your yield doesn't increase save the electricity. Alternatively, your yield may not increase, but you may be able to shave some time off the veg cycle which would result in an electricity savings.
Food for thought. Happy growing.
. I may not quite make it this time as I pulled 3 plants and put them under the HPS midway through flower as I needed to space my fixtures out more.
