Help please

My 11 day old seedling is turning brown at the tips of the the single blade leaves that come out after the baby leaves not sure what it is. Please help! But the top leaves are fine so far

Its being grown in a PC box with three others under 59 total watts cfl, in sunshine mix 4 and this is the only one doing this.

Nutirent burn. Leech your soil and use a mild form of feeding. Also recalculate your feeding regimen and dilute it to reverse it.

you sure its nute burn i didnt give it anything and none of the others have it?

and what do you mean by leech, you mean flush?

Seems like magnesium lockout,not really nutrient burn. Nutrient burn occurs mostly on tips of new leaves. What pH are you watering with? Lockout occurs above 7 usually. Please tell me you are not using tap water.

Used tap water for 10yrs........

When I leech I use a product called Clearex there is another good one for leeching called final flush. And yes it is a flushing agent that has complex carbos in it.