Hello, today at morning that edges of my plant sta...

I didn't use any nutrients at my first grows. A bit of yellowing at the tips is normal in my opinion, especially when it's close to finish. Overall looks great, they are nice and frosty and lucky they didn't stretch that much.👍

Hey there that's a phosphorous symptom you can tell by how the yellowing is happening , probably it's a lock out as you know , cutting out the pk boost for some time is a good idea probably you won't need it until the end , plain water helps with this a bit but I don't really like flushing because it can cause water stress kind of for the plant. Hope this helps get it under control! 🚀

It’s possible you gave them maybe to much Nutrients. Also some plant change tellow at the end of the flowering.