Overnight burn on day 16

yes anytime u feel you have burnt your plant a good flush is always a good idea.. but at that young of an age there should be no burn.. you should only be feeding ph water and have that baby coverd with a clear plastic cup.. i use my old Macdonalds coffee cups.. they work perfect.. no need for humidifier and all that at that age.. just light,fan,and a lil dome of sum kind and you are good to go for 3weeks..atleast..

I think that she's just getting too big for the puck.. I recommend transplanting to a bigger home.

Your working a bit against yourself I fear. The little guys don't need any nutrients until the second set of true leaves emerge... While others on the site feel this approach is wrong... It's widely recognized amongst Hydro Growers that this is how they like it. So for five days after all five of my seeds emerged I did not feed any nutrients. Also you should be prepping Peat pucks before use with cannabis. Part of the reason Peat pucks are so widely used for Cannabis is because they are naturally Acidic so if you water with a ph of 7 this will bring your actual ph closer 6. Sometime people can screw themselves by assuming their soil ph is either Acidic or Alkaline. And someone giving you advice with Alkaline soil would be correct if in saying they need to adjust their PH to 6 or possibly lower.. There is a lot to actually growing plants period.. And folks tend to oversimplify.