yellowing and stunted growth

This is my first grow I am into my 6th week and all was well till about two weeks ago. Leaves started yellowing from the bottom up. I flushed them twice thinking nute burn.

After that someone suggested N deficiency. So I bought fox farms grow big 6-4-4.

Have been through two nute feedings. Still dying on me.

400watt ups
4-bulb 40watt full spectrum fluoro's
Humidity-50%
Temp-76night-83day
Runoff ph- 6.4
Soil ph- 6.5
24hr light cycle


First picture is right before yellowing started

Okay apparently I uploaded wrong....there is not a picture before the incident. And also this two different plants. They are all doing this btw

Keep feeding normally and watering. Seems N deficiency was the problem. Give em a lot of love.