Whats causing this?

207 Genetics Sour Diesel Auto, day 12 in FFHF.
TS1000 Light at 18" ,78 , 50 % rh, no nutrients yet, just ph’d water at 6.

Welcome @cachemoney22. I don’t know where you posted your question from. it would be easier if you post a pic. You’d need to log on here from a browser (phone or computer). Cheers.

Welcome to the community @cachemoney22!