What's causing the leaves to lighten?

Salut Mec, On voit clairement que c est un debut de brumure suite a un exces de nutriment . Attention dans les premiers jours, si ton substrat est riche il est inutile voir dangereux de donner trop de nutriment a cet age les racines sont fragiles donc tu risques d avoir l effet inverses car trop de nutriment risque de bruler au pire, sinon de ralentir la croissance. Perso quand j'utilise des substrats enrichi ,je fais une poche de lightmix au niveau de la pousse pour éviter ce genre de réaction. Bonne et merveilleuse année 2021 avec plein de verdures et de fleurs. 👉🤩🌱🌿🎍👨‍🌾😁😁

Too many nutrients at this stage of growth. Growing in ffof, you don't EVER add anything else for at least 3 weeks, that soil runs hot as it is and adding additional nutrients is just going to cause problems. Ph'd water only for a while until she tells you she is hungry. Happy growing.

Hey Bro, The Fox Farm Soil is heavily pre-fertilized, isn't it? Looks like a combi of too much water (wet soil) and starting nute-burn. Keep going with pH'd water, think it's the best way. Decrease the amount of water when top feeding. Go for a decent shower everytime shortly before the lights go out. When they are small they tend to drink more via its leafes than via a not fully developed root-network. Good luck and happy trails for the rest of the way🤞.. Servus OimRausch

Don’t give her cal-mag at this stage! Burns the plants. I got the same problems before. This cal-mag product is very strong.