looks like nute burn but ...

I've been treatin my plants the same this is my first grow with multiple plants had a few problems but over came them my biggest tallest plant has a few leafs about 2 thirds the way up with some tips a. Bit brown . But haven't been useing a lot of anything mainlyjust tap water the whole grow the main stalk is also rather red I'm two weeks from harvest so don't want them going wrong now : / any help will be great ... Peace ; )

in my experience if your 2 weeks out theres almost nothing that could go that wrong, but I always have just about all my tips like that, main question is how close are your lights, what watt, temp that kind of thing. when you say tips of them im guesing you mean only a couple centimeters or so?

Ye just about a centimetre I've got two 600 watt hps about 28 inche above plants running about 27 centigrade I'm woundering if it cud be were I've just started letting the soil dry out comppletley so maybe the plant was bit dehydrated causing leaves to burn a little ? And u have any idea about the red stalk