that's a heavy duty LED light. 650W is powerful.
I think that the 12" hang height has something to do with how the spread of light is emitted from the lamp itself. eg 100% at 50" is less even in the canopy then 40% at 12" if you where to look at it in a PPFD map layout.
I use a 300W led setup and I hang them aorund 12-18" but they are 100% on all the time no dimmer and they are not as efficient as your light.. so 650W at 40-50% at 13" does not seem to far off to me. and I would continue going with that. Can always bounce it up 5% and see how the plants react.
The hand test is a good option. place you hand where the canopy is and if it feels to hot on your hand its to hot for the plants, warm is perfect.
Good Luck!
===
Seems I have a fake troll account trying to cause shit by emulating me.
They even went as far as to copy my profile picture and response to there troll lol. Someone sure is but hurt.
m"Q"use is not
@m0use Q vs 0. Q is fake like Q-anon
Sorry for their rude comments on your question.
I have no idea who they are or why they are doing this.
Please hit complain and report this to Growdiaries.
The real m0use profile is 2+ years old in age and has a higher rank. It's got the gold emblem on it, easy way to tell.
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