Need help identifying nute deficiency

These plants are just a little over a month old from seed, check my journal for setup details. I have noticed that one of the plants has started to yellow from the bottom leaves up, dropping a set once every 3 days or so. I just watered so I can't feed it yet. I did give it a foliar dip in Magnesium and Calcium enriched water (1 tsp Mg + 1 cup of dolomite lime mixed in w/5 gallons of water). I just added the mix to my spray bottle and misted the affected leaves.

I have also noticed some of my stems are a reddish purple. I know that this can be a result of night time temperatures dropping (mine run about 67F). I also know it can be a sign of K deficiency.

What do you think?

bump, they are droopy, and I don't wanna lose 'em!

Plants grow fine with no nutes at all. How often do you water and what is your setup?

mambokabui said:

Plants grow fine with no nutes at all. How often do you water and what is your setup?

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water every 3-5 days when pot is dry, light is 600w HPS 26" above tops, temps run 79F day and 68F night. no nutes yet, but in MG potting soil w/ 50/50 perlite.

It seems it should be draining well with 50% perlitemix
does pot have holes?
do you have a plate under the pot that the water drains into?

do you let the pot dry to the point that the pot feels light?

yes to all of 'the above. When I watered yesterday I noticed that I have a decent amount of roots showing through the drain holes. I think my issues may be related to the plants being pot bound. Going to move up to bigger containers today and see if that helps