Need help diagnosing plant

Hello All,
please help.
Overnight my OG kush top fan leaves started to turn brown as in the pic. I cannot for the life of me figure out what is wrong.
I am growing in super soil. I made sure the light was far enough away. I thought it might be light burn from my sk600. Or wind burn from my fan. I moved both away.
Anyways, any ninjas on here can help me!

Looks like it may be a bit of a nutrient lock out.
What is the pH of your runoff?

what we are shooting for is a runoff of about 6.5 pH.

I usually pH my water at about 5.9, that way the pH of your runoff is around the 6.5 pH that we are shooting for.

If all else fails, flush and start over.
When I flush, I run water through the grow media until it runs clear.

Don't know your grow system but veins remaining green like that is Magnesium shortage.

Yes, pH out could cause it ...

What I've seen with super soil is that since the soil is so hot it tends to send the pH out of whack, and sometimes locks out nutrient uptake. Again, pH being out of whack can lock out nutrients. check your runoff pH.

If it is not up taking nutrients, then it would stand to reason that it would also have a deficiency in Magnesium.

Super soil has all it needs in it, but the problem with it is when you mix it, you have to let is cook (because it's too hot when it's fresh) (either in a container like a trash can, or wrapped in a tarp, turning it every couple of days.) and give time for the nutrients in the soil to start feeding the soil. After about a month to 6 weeks of the soil coking you will notice a little mycillium growing in the soil (that's when it is ready.) By the time the soil has cooked, the pH has settled down.

My point is that if he used freshly mixed super soil (which has every amendment under the sun and would have plenty magnesium in it) , and if the pH is too high, it will lock out.