Top leaf yellow and stem turn purple

> I just stop nitrogen weeks ago Why did you do that?? Of course the leaves turn yellow if you stop giving your plants nitrogen. And purple petioles indicate a phosphorus deficiency and it's at the start of flowering that your plant needs it most. In short: feed it. Also, you've got several diaries running in parallel, so it would be easier to work out what's going wrong if you asked the question directly from the relevant diary next time.

Your stems aren't that bad man. If the red stems you are referring to are the leaf stems, pffttt relax. It's the red stalks that are more of a thing to pay attention to. Thats gonna be a lack of Phosphorous. Now what is causing that lack in Phosphorous is the real challenge in solving. But i don't see that in those pix. Nitrogen takes more than 24 hours to green up deficient foliage man. It can take a week to 2 weeks for a full green up recovery. Look at my current diaries. When they were planted they were root rotted and grossly under fed. The root rot wasn't part of the plan but the under feed was because i miscalculated my harvest by a week so the clones were cut a little earlier than they should have been, so i tried to slow their growth as much as i could and that meant stopping food. Your soil is probably due for a flush anyways. Doing that around week 3 of flower will ensure a smooth sail to the finish.

Phosphorus is the red stems usually give it a nice nertrituon mix and if your in the flowering stage low nitrogen and a good amount of potassium phosphorus and you should be ok