Plant leaves turning yellow and getting brown spots

[Patimat]

Hello!

First time grower. My plants have been healthy for the first 4 weeks and after they started having these brown spots on them and are a big yellowish.

I would be grateful if someone can help me pin down the problem so I can use necessary measures.

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[Gingerbeard]

Hey-ya Patimat What's your nutrient and pH situation? Do you have a picture of the whole plant to see where it starts and stops? Have you taken a magnifying glass or loupe to the bottom of your leaves?
Just a few common queries. Although I think someone else is going to tell you what's happening.

 

[billyboy]

https://www.growweedeasy.com/cannabis-plant-problems/calcium-deficiency

Time for CalMag

 

[Gingerbeard]

See. I told you someone was going to give you the answer.