Advice on red stem going through the brain

Parece exceso de riego , deja que se seque bien el sustrato antes de regar. Si no baja la dosis de nutrientes. a ver si mejoran!

All of these point to a classic case of low temperatures. Maybe its dropping too low at night? Red stems could also mean you need more phosphorus. This is especially true if your plant is a couple weeks into flower. In this case, the drooping would indicate another issue (I've had plants that would only droop a couple hours before lights out and perk right up in the morning. That is ok!). If the only part of the stem that is red is the part facing the light, thats a natural sunburn and is fine. Again, this would indicate the drooping is something else, maybe overwatering. As always, check your pH and EC regularly to maintain a healthy girl! Good luck!!

Hey, I took a look at your diary and it seems like the droopiness is caused by water damage. Try increasing the amount watered to about 2.5-3 liters (since you are growing in 11 liter pots) but while doing that make sure to irrigate them only when the top 5cm of the growing medium is dry (don't let the medium dry out completely), this is usually once every 2-3 days or even 1-2 days during late flowering. And the key to prevent water damage is to make sure there's proper drainage! so make sure there's at least 20-30% of the irrigation solution as runoff (checking the runoff EC and pH can also help you keep track of your soil fertility. As for the purple/red stems- as long as there is no sign of deficiency (which is usually Cal/Mag) then its just a sign of Nitrogen (N) abundance, that is totally normal! and even healthy! *btw for better answers to your questions I'd suggest taking pictures under normal lighting since foliage coloration is very important to identify deficiencies/toxicities. Hope this helps, good luck! and happy growing :)