Is my plant sick? Purple stems? check out pics>>>

So we started growing and the plants we have from the original seedlings (the seeds were from buds i smoked in the past, strain unknown, all plants different)are doing great, they look great, starting to smell also..

the only thing is that they are starting to develop purple stems..

Is that a bad thing or just the strain of bud?

also we aquired a bigger plant from a buddy and the leafs are starting to droop and turn a yellowish color, also the stems are purple once again. use the pics and let me know what u think...

thanks appreciate the info.
peace.

What is your nute schedule. they look hungry

I've grown two plants before so im not an expert, but both were from bagseed and both stems got purple at the parts that the light hit. The parts that were shaded by other leaves were still green, hope that helps!

and the ph as well.

im growing with potsim....ph is 5.4-5.8
we are using GH 3part....the babies are about 2 weeks old using very low dose-less than 1tsp per gal

the bigger one is about 4 weeks old but has been transplanted and is showing slow growth. nutes are 1.25tsp/gal....the tips of the bigger one are turning yellow/brown. but it is just the very tip. it is not turning the whole leaf colors. the tips of the baby fan leaves are even a lil yellow. is it nute def or nute burn?? need some help. just raised the lights a little bit too. any help is greatly appreciated. thanks and peace

I usually don't use ferts until I see at least 3-4 nodes or they start to show the slightest yellowing in the lower leaves. yellow tips are a form of burn. I would flush with 5.8 p.h. h20 and wait a day or two. I went very slow with the nutes and my plants have turned out very well.

ya im bout to put it in pHd water(5.6) and leave it like that for a day or two. then ill add a low dose of nutes after that. prob a tsp/gal and its in about 1.25 gal of water. its our test run so when i get my seeds i wont use fert for about 3-4weeks. thanks so much for the input. peece

I wouldn't even put that much in. is that 1/3 of what GH recommends for veg? I would half that or even 1/4 it and increase slowly.

ok well the first one they have on the bottle is 1/4 tsp per gal...so ill do that. how long until u increase after that? like every week or so?

Only you can make that determination. Every plants genetics are different. I never go by the bottle but from what I see. There is enough info on this site and smart people to help you out with every problem / deficiency there is. Never go up by more then 30% at a time though or you will shock them. Sometimes you might need to cut what the bottle says to put in, into much smaller fractions.