Help! Deficiency?

[Crane]

This is an OG Kush fem seedling, 22 days on 18/6 today. Yesterday I noticed lower leaves starting to get pale, those brown spots in the middle of the leaf and the leaf undersides are a deep red? It's growing in soil, got it's first nutrients maybe five days ago, 1 ml of Biobizz Grow per liter. Temps are high-ish 30C when lights on and about 20C lights out. Thanks in advance.

 

[3fingerdSean]

Biobizz is for coco or pete. So save it for those substrates where you can have success. I keep mine refrigerated after opening since its plant based. Ok to fix this I would recommend going with a chemical fertilizer, something simple like a 10-10-10 with a teaspoon of sea 90 per gal. You will need to add cal mag, Epsom salt , molasses ect as you go. Also soluble mychorizzae helps. Be sure to check the runoff ph and get it to 6.5 using lime or soil acidifier & get them into larger pots.