Blätter werden gold und Rollen nach oben?????

Looks like a calcium issue. It's still too early for the leaves to be changing naturally like this. Calcium issues usually stem from either not using a calmag supplement (especially with RO water) or too many bloom nutes could cause a lockout. Other possibilities include high temps and low RH causing the tips to dry out. Start with fixing up your pH. Your perfect for hydro, but for soil you should be up over 6.5 right now. Basically, soil starts around 6.2 and you slowly increase to 6.8 over the course of the grow. A slight pH problem like this shouldn't cause a much of an issue as you're seeing, but its a good place to start!