Brown/yellow dots on leafs

So I had this Royal Gorilla Auto by Royal Queen Seeds for exactly two months but now it’s showing some weird dots and it doesn’t look very happy/healthy. You can see best in picture one, the leafs turn yellowish and curl up, the tips are bend as well and completely brown.
Anyone know how to fix this or what it is?

I’m using 10L normal soil, BioTabs fertiliser and a Spiderfarmer SF1000. I water with plain tap water without any additives.
 

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No I don’t check ph. I read a threat where someone said that you don’t need to ph water in soil because soil has some buffers.
 
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