2nd Grow - Brown leaf tips... only 2 weeks in

I just started my 2nd grow 2 weeks ago (indoor, in soil), and am noticing a problem. I have 6 plants, and all but 1 of them have brown tips on the leafs. I'm using water with a pH of 6.8 run through a Brita filter (pH measured after filtration), and soil with a range of 5.5-7 pH. Lights are CFL, on 18/6 schedule.

Plants are all in ~5 liter containers. I have no idea what I could be doing wrong... I've done so little, I can't really think of anything. No nutes of course being that it's so early.

Does anyone have any ideas?

Could you post a picture of the whole plant please? Also what soil mix are you using?

Here are pics of 2 different plants.


Mix is:
N - 100-250 mg/liter
P2O5 - 100-250 mg/liter
K2O - 100-250 mg/liter

They look good IMO, The mix is probably too hot right now for the seedling as it's showing burned tips and the soil looks too moist and compacted. Has growth stopped?

No, growth hasn't stopped at all. I just noticed the tips today though... hopefully it doesn't get worse.

You're safe IMO