Red Streaks on Stems and bright yellow/green new growth.

Hello my friend, the plants are looking good indeed! Nothing to worry about, the stems can turn a bit purple for all kind of reasons and yours do not turn purple from a deficiency. The new growth is also looking perfectly fine, again nothing to worry about. Enjoy this grow buddy, you are doing great!

One more thing. Sorry to spam but i forgot to mention it. Recently i was watching a Harley Smith interview where he spoke about this very thing. Growth tips looking pale and yellow, especially when the lights first come on in the morning. Harley, who is a botanist for a huge cannabis business called N-P-K University i think, he says that the growth happens when the lights are off, and because there is a lack of light there is no photosynthesis happening which will turn the foliage green. Look at your plants next time the lights come on, or better yet take the best pic you can. Then go back 4 hours later, you'll see things got greener.

The new growth being slightly yellow or a faded green is typical of new growth. As the plant grows it will green up as it makes way for another set of new leaves. If the problem doesn't resolve and gets more pronounced, and takes on that faded colour throughout the plant then you could be lacking in sulphur, but it's not likely unless you have a pH issue. If the yellowing is only at the growth tips, and but not everywhere on the plant, it's likely a Iron Deficiency. If thats the case then a little calmag will help. It has nitrogen, calcium, magnesium, and if i remember correctly it should have a little iron as well as suplhur, but i'd have to double check. Overall i still think your looking good.

Red streaks could be genetics or could be a sign they want more Mg or P. The yellowing could be from a need of Sulphur or Iron, this could be from PH or its lacking in the feed. If it greens up in a days time then nothing to worry about as new growth will be a bit yellow at the start. When feeding with liquid nutrients its best to use EC values as its concentration, its universal across the board. Also good to get some runoff with it as it can buildup in the medium and cause bigger issues over time. It appears they are well feed but typically they get fed the same thing all the time unlike the CaMg every 3rd week kinda thing. Not to say its not working, just different from the norm I have seen here. Good Luck!