Yeah doc same here but this is a very first ive seen this on any of my plants. If its potasium. What method should i use?
For your next grow, get a better soil than MG. I would flush, as recommended by 420God, but you have timed release nutes in your soil which may compound your issues. If you aren't feeding them anything, try a mild dose of a
complete fert. What is baby bio and what is the NPK of it? Does it contain micronutes (trace elements)?
This is why I really don't try to guess what a deficiency might be anymore. Some of them look very similar and everyone has a different opinion as to what it might be.