problem with fan leaves help ?

is it common for the bigger larger fan leaves to turn yellow and fall of becuse it happens to me every grow right about 4 weeks into growing is it just the plant shedding them or is it an underlying problem i've even tryed giving them full blown veg nutes before and it still happens

oh i meant to say 4 weeks into flowering

Completely normal. I was just searching for the terminology and the answer as to why the old leaves die off, but regardless this is normal in the flower process.

But now that I look at your pics, it's hard to tell with the lighting but they might have a little nute burn. Kinda guessing though based on the pics you provided.

ya the tips are a bit burnt im currently using GH nutes at half strengh