Red stems on 5 out of 6 seedlings

stop overthinking they are fine.

Perfectly normal and nothing to be concerned about. Temps are not a factor. Hope this helps,......... Organoman.

Is perlite a soiless medium? I use nutramix hp with perlite. But it is a peat based product. Therefore it is called soiless. If your not in actual dirt then your grow would be soiless as well. Now the ph levels differ for soiless and dirt. Right now your set for dirt with your ph. With soiless ph needs to be in the 5.5 to 6.0 range for veg cycles with 5.7 or 5.8 being the sweet spot. In flower 6.0 to 6.5 with 6.2 to 6.3 being the sweet spot. Babies can be fed 400 ppm 0.8 ec. Every week if you see good growth the ppm can be brought up 100 ppm 0.2 ec. Max ec levels for grow cycle is 8 to 900 ppm. 1.6 to 1.8 ec. Cheers