why my seedling yellowing

why the bottom/older leaves turning yellow?
they are under 300wat cob led (35 inches) is that a light stress?
or nute deficiency, over watering?
iam growing in soil and watering with a tab water

We need more info. What kind of soil? They look hungry (cots are yellow)but those are big pots. In the pics, except for the cup it looks bone dry? Give us more info

They look a lil dry in the pic, maybe a good time to feed them if you're not already doing it. Nitrogen Deficiency is whats making them yellow like that.

Is tab water a typo? If you are watering with tap water, does it have chlorine in it?

CunningCanuk said:

Is tab water a typo? If you are watering with tap water, does it have chlorine in it?

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My plants love my chlorine tap water.

twentyeight.threefive said:

My plants love my chlorine tap water.

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RO filtered water made a big difference in my plants but our city water is really nasty.

Pot too small, do you have a 200 gallon pot? lol

Where do people get these ideas to start seeds in huge pots? comedy

visajoe1 said:

Pot too small, do you have a 200 gallon pot? lol

Where do people get these ideas to start seeds in huge pots? comedy

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Experts on YouTube cause nobody would manipulate a YouTube video

Not sure it’s the cause of tour yellow leaves, but you want to get the temp & humidity up for this stage 18 is pretty chilly I would think

Username85 said:

Not sure it’s the cause of tour yellow leaves, but you want to get the temp & humidity up for this stage 18 is pretty chilly I would think

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I didn't even notice that in the pic lol.

Username85 said:

Not sure it’s the cause of tour yellow leaves, but you want to get the temp & humidity up for this stage 18 is pretty chilly I would think

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Good catch especially if that is lights on

In gonna assume that the floor is probably a lot colder than the air in that room too. Too cold root zone = bad news bears.