Need Help ON plant Issue

Hey Guys .. I need some help My plants are at day 39 from seed under 12 /12 light from seed / 600 watt HPS .
. Everything was fine until 8 days ago looks like they stopped growth and leafs are yellowing and turning funky

Soilless Useing LG`s mix 4 parts canidaian sphagnum peat moss/ 3 parts perlite / 2 parts worm castings / 3/4 cup lime .. Mixed up 2 times per week for 5 weeks before use

watering by hefting pot weight once week average no nutes used yet/

watered with ph adjusted water at 6.0 ..

I had used molasses 3 time at watering at 1 1/2 tbs per gallon at ph 6.0..

temps light on 72 to 76 degree & 60 - 65 lights off

. the larger plants are 39 days old smaller ones 2 1/2 weeks .. Some look great some are looking bad all the same soiless mix all watered the same ph balanced 6.0 water at the same time .. AS You can see I need some help on this one Thanks alot guys

their saying what the big plant did in Little Shop Of Horrors....."FEED ME!!!!"

why are you keeping the ph at 6.0?

Thanks guys going to feed These ,, And see how that goes .... and I use 6.0 in grow then to 6.2 6.4 in flowering in soiless

You know it seems strange. Everyone worries about PH. I have great success growing, thats a small cola from last years outdoor grow on the right. I have NEVER owned a ph meter and never have tested a single drop of wate or runoff. Am I the only one that doesnt have PH issues.