Secondary stems turning red

Hello everybody,I have recently come to notice that the stems that branch off from the main stem at the top of my plants are turning red. I have 5 plants growing 2 feet from a 600 watt hps light in a tent thats 70 degrees and 35 percent humidity. I am not currently using nutrients, but i have the general hydro. flora series. I am, however, using 2 teaspoons of tiger bloom every 3 days. I have 2 fans in the tent, one pushing out outside the tent. I water the plants whenever they are dry. Are the stems red due to a nutrient deficiency? I've been using only 6.0ph certified tap water. So why are they red???

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how old are the plants? how long did you flower them?

This is either deficiancy, too little oxygen in roots or cold temps.

and flowering plants need fertilizer!

the plants are 60 days old. Theyve been flowering for 2 weeks. It's only one plant that it's getting severely red on, but its developing on 2 others. I am giving it bat guano every week and tiger bloom. Must i need more nutrients at this stage of growth? temp is 73, humidity 29.

you could try to add a bit more P since P deficiency = red/purple stems. also you are supposed to gradualy make the fertilizer dosage stronger untill around 6th week.
Overall i dont think its anything you should worry too much about since your plant looks fine except for the red stem.

With some strains i grew they always turned a little red/purple from genetics so this might also be the case. especially if the plants look fully healthy.

Also its very hard to see in detail with the HPS light on. try taking pictures in white light .

best regards