SOIL Leaves turning yellow

[webanator]

I just switched to bloom 3 weeks ago, now my bottom leaves are turning kind of yellow from the bottom of the leaf heading to the tip.
I’m using super soil, no nutrients and RO water at 6.3ph
ill add a picture of the actual plant if needed. I cut a leaf and scanned it to show the color lol
im using a 600watt led, 4x4x7 grow tent, 8 inch exhaust fan, two clip fans inside circulating the air.
It shows up way more yellow in the led lights though

 

[Tersky]

https://www.growweedeasy.com/cannabis-plant-problems/magnesium-deficiency My guess

 

[NikkiAnne]

How is it doing now? was it a cal/mag deficiency? I heard that can happen using RO water if you don't add some