I also use LED's bro, I've got no idea how high that light should be, I've never grown with MH/HPS.
From what I've read here if you can feel the heat from the lamp on the back of your hand it's too close to the plant, probably even more so with seedlings, but 2 feet is a decent height.
I'm sure someone will help with that question.
And I'm like you. Don't tell another living soul.
The fish that doesn't open its mouth never gets caught.
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