My plants are in grow stage. Things have been going really good lately. Now all of a sudden the stalks are turning a purplish kinda color, going up the stalk. Some of the stems have a dark purplish color too. WHAT IS THE PROBLEM? I have looked at a few sites but all the info conflicts. I really do not want to kill them (duh) lol. They are under a 1000 metal halide bulb and I am using the general hydroponics feed schedule for mild growth. They are beautiful, growing, producing new leaves, no bugs, some of the very tops leaves are faded yellow though. Any help/suggestions?

They are in growdan/rockwool medium, and am using a recirculating water system. They get watered 3x day, and light is on 16, and off 8. (grow)

Just off hand, some strains turn purple because of my A/C being cold. Some turn because just not enough nitrogen. Then some strains the PH may not be where they like it and not uptaking nutrient.

The trouble shooting form will get you more help.

If you have A/C and it's around 70 degrees and everything has been going alright and they are still looking good and growing then it's the temps. Nothing to worry about.

Well i am only growing sweet island, and my room sits around low 70's. Now when they were in rooting the temps sat in 80's. Do you think I should try to warm it up a bit more? I honestly cant see how the nute thing could be a problem, they are getting massive amounts of nutes, I am using general hydroponics schedule for mild growth. So they are getting all the necessary nutes, and I change it out every 7 days. They are growing, getting bigger, and producing new leaves. Just the stalks are going purplish, and some of the stems. It is always something with these girls, this is my second run. I am learning as I go lol. Not much else I can do eh. I really would like to get diesel again but cant find any.
I love you guys! I need a partner in crime to work with. My last partner was a tard and screwed me (buh bye). Ohh well, atleast I can turn to you guys for great advice!

Dont worry, My stalks have purple lines in them as well.

sweet island?

picture is worth a 1000 words but like Loc said fill out a troubleshooting form and there are lots of readers here that love to help.

I feel for you about the partner. Brother was mine, there ain't nothing like being screwed by family. Brother in law wants a chance but now I don't think he is any better.

If your temps are about 70 and everything else is good including water temps then it is the strain and being cool. No problems. Some do it some don't.

If you show us a pic. I will show you mine. Papaya with purpley stems but Hawwiian and redhair skunk in same room with same nutes all green.