Medium Stress

New to this. Have been struggling with seedlings that start strong yet by the three week point begin to deteriorate. All the symptons pointed to nutrient deficiency yet with PH fine (6.6) and nutrient levels seemingly good I was stumped. Reading I stumbled upon Jorge Cervates (?)_ description of medium stress and I ticked every box. I'm using a readily available (in Australia) commercial potting mix - Seals Premium - and 5 in 1 manure blend with Dolomite Lime added. With plants at the 3 week and 6 week stage (long story) my question is now I know what the problem is how the hell do I fix it? As I said I am a complete noob so any help is gratefully appreciated.

You are probably burning them with the manure blend. Just let them go for the first 3-4 weeks in soil alone, then add nutes or manure once they are established. Good luck mate.

thanks for the advice wolf.