Stickstoffmangel?

I've taken a look at your diary for this grow and I don't think your temps are too high - I think they're fine. I also don't see any problem with the nutes - you've been consistent. PERHAPS you could check your ec of the runoff to see what it's reading so you know whether the plant is in fact eating the nutes you give it... but I just don't think that's the problem. So I'm going to go out on a limb here. I'm more concerned about the brown spotting I see on the leaves... this is NOT normal and NOT caused by any nute problem or issue nor do I think they're caused by you dripping something on the leaves and them burning because of that. Combine the brown spots with the lack of vigor and the yellowing of the leaves and my mind goes to something like septoria. Now, septoria can look VERY different so if you google "septoria in weed", don't take a look at only one picture of it and say "nope, that's not what MINE looks like" .... hit the "images" of that google search and you'll see the wide range of what it can look like. Then start reading a COUPLE of articles on the subject before making your determination. I hope I'm wrong... Good luck!