I didn't see the guys bucket, but most are plastic. So won't radiate much at all.
The 100w led lights in my last post were looked over by Big Clive. Specifically the one's with a yellow sticker at one end. They started at 100w but dropped to 71w as they chips regulated down the power due to heat. The chips reached 125c which was 110c over his 15c room temperature.
This is good news. That is hot enough to be worth cooling, while still not needing the cooling to survive. It's also next to no work. With little expenditure.
I'm very fond of RV pumps. £10 gets a 50w pump with 10 meters of lift. 1/2" hose just pushes on. Such a pump will circulate with quite some force. Good for trials. Long term a central heating circulator pump is the real deal. Less pressure, but harder to kill, and very quiet.
My next project is my 3rd air cooled Led system, but I'm still looking at this. One common goal is to get maybe 6 or 8 cob's together, to light a meter from a fixed point. So just a shoe box sized light, without a lot of connections.
The pic is the published data of my citizen 1212, though it's no way such a circle imo. I have laid a second over the top at 90 degrees. To look at lighting a meter from about half a meter above. The 30% gain in the middle, is over maybe 200mm of the canopy, so maybe the leds should be 200mm apart. Then the perimeter can be improved with the shade. It's work in progress, shared now as maybe it's been done?