Is that “15,000 lumen high bay light” you bought “a while back” an LED light? Even at 1 watt per every 100 Lumens it’d be kicking out 150 watts, and an older unit might not be quite that efficient.
In any event, yeah, 15k Lumens should start lots of seedlings. ;-) That’s kinda what I have in mind with these two (rated) 8000 lumen lights — or, I may try seeing if they’ll further reduce seedling “spindlyness”.
My old heat sink grease is rather dried up, but, it turns out “SuperLube” has a very good deal on a 3 oz. tube of heat sink grease: $11.65 on Amazon. It’s probably not quite good enough for cooling the latest and greatest Intel CPU’s, but, I figure LED’s that survive an hour without heat sink grease for their obviously intended & fairly decent heat sink will last 10 years with “pretty good” heat sink grease. :-) This stuff is silicone base - it should hold up practically forever, and 3 oz. will last me a good while. Then again, almost nothing I’ve seen from China that should use the stuff has it, or has it properly applied...
I don't buy into that watts equivalent thing but this thing is supposed to be 500 watt equivalent. I go by how bright it is in the real world. I didn't know that high power LED drivers use thermo-grease but I suppose it makes sense. I still haven't gotten away from that seedling “spindlyness” yet. I see pics where people are growing nice squatty plants under not much light and/or lights that aren't up close to the seedlings but all mine are daddy long legs. Maybe I should try this high bay light as a grow light.
Yeah it's LED and I originally bought it last year to light up the high tunnel but not as a grow light. Just to light it up at night as I finish building it and later on just to have light in there without installing a dozen fixtures. Since the peak is 16 foot up, a high bay light was the answer. It was a closeout at homedepot.com and the last one they had. ETI Lighting brand. Funny thing is that even thought it's a discontinued model, they still use a pic of it for their website, etissl.com.
I really wanted a second one since the tunnel is twice as long as wide but never could find the same one. Seems I bought the last one in existence. Someday I'll pick an equivalent model and get another for the tunnel and one or two for the shop/barn. I like the ease of installation for the round ones with single hanging point.
It's China but "good china", not no name fly by night crap for the dollar store. All their stuff has a 5 year warranty and according to about page, they use Samsung LEDs. https://www.etissl.com/about-nvc-international/
Of course that 5 year warranty probably doesn't apply to my closeout purchase from homedepot which now follows the amazon/walmart "marketplace" model which use to be called drop shipper. Regardless, if a company has a 5 year warranty and have managed to stay in business, it must be decent stuff.