Browning of tips of leaves!

I have a three week old plant, which has been fed Miracle Grow (15-30-15), from day on in a diluted solution of 2 Tbsp per gallon of water. I have the pant in a hydro system (Aerogro Classic 7) the light is set for herbs and is placed in a way the fan in the room flows air constantly. Room temp is between 82 and 86 degrees and the lights are broad spectrum grow lamps. The plant is 5 to 6 inches away, so I do not think the lights are burning the tips. Any ideas on what might be causing the browning of the leaves?

A picture tells a thousand words.....

where are pics ?!

holy shite, ok never ever even 1tbsp of MG per gallon, i say only use 1tsp because its about "1/2 strength". its safe to use 1/2 strength every other watering and this will give you the best results since plants grow the test with 1/2 strength. 1/4 strength and 100% strength only stress it.

you need to flush with a 1/4 strength nute solution. make sure to get a lot of run off, the reason you want to use weak nutes to flush is so that your plant wont starve.

Hey dirty..... Do you have a ppm or ec meter?

I'm just wondering what the ppm of the recommended feeding amount of MG is?

Here are some pics and other than some test strips for PH and Alkalinity I do not have anyway of testing at this point. Could yu suggest a tester that wont break the bank?