Brown patches on a leafs - 10 days old veg

[Nothingtodeclare]

Hi everyone,
My plant has a problem : huge brownish patches on a bottom leafs.
On Sunday I recognized the little brown-yellow dots (1-2 per leaf). To be honest - I was thinking that is just little dirty or I left drops of water. Any way I have 6 led bulbs b22, so I was sure this is not dangerous for plants. Nvm.
Yesterday the patches was much bigger :
https://ibb.co/mVD4aw
https://ibb.co/cojz8G
I’ve read, that could be def of water, wrong ph or def of calcium.
So I changed ph of water to 6Ph and I flushed pot plenty.
Today morning these leafs looks worse :
https://ibb.co/etj98G
https://ibb.co/e8FhTG
Because plant is bushy not tall (6cm high) I shouldn’t give her any nutrients but do you think, could I buy in pharmacy pure calcium, mix it with a water and prompt a bit to plant?
I watched over plant and I don’t think so it could be spider mites.
Guys, please help. I’ll really thankful for any suggestions.

General plant looks healty.
https://ibb.co/hHDfFw

Oh, I forgot :
In a box I havr temp 26.5-29 degrees, 45-70% humidity, over 9000lm.
I’m watering plants every day, but a little bit, after lights off.

Take care,
Ann

[MrChedHead]

Hi what medium are you growing in?


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[Nothingtodeclare]

Soil mixed with coco fibre. Soil which one I have is : Miracle Grow Peat free All purpous Enriched Compost.

[MrChedHead]

I cant really help with that as im just a coco grower... i know a lad who using soil coco mix hopefully he be along to help you out


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[Nothingtodeclare]

Oh don’t worry, thank you any way