Plants are about two weeks old and were going really strong, about two days ago I started noticing the stems were purple, leave tips started drooping and now the new leaves up top are starting to brown in the center. I have no idea what's going on. I added about a 1/4 of the nutrients I was supposed to at this stage so I didn't think it was that. My lights are where they need to be. Also I'm using straight perlite (the soil that appears there is a jiffy pellet) so I don't have a problem at all with drainage. I am stumped and I lost my last batch of plants due to the same thing. Now what I may have it boiled down to is my ph meter. I have a feeling when I programmed it that I may have not got it exact when using the distilled water and the two packages that it came with. Could ph possibly cause this? I order a new ph meter to test my theory. I just really need help as in my seeds that I have were not cheap. Thank you for any ideas.