What is causing this dead spots/holes

What could these be caused by? Sometimes temps drop down to 15°C when lights are off. And I notice these after almost every lights off cycle. Could these be from low temps?

Only the new leaves seem to be affected and feeling like growth is slown down too.

Maybe Manganese Deficiency? Almost everything matchs up with that. I was having some drainage issues with the cheapo fabric pot that I got. Could that be because of that?

Nice pics. It took me awhile to find the damaged spots tho. Mainly because mine are similar but more damage. My 1 week veg clones have 1/16 - 1/8 round holes on middle aged leaves. Also dead spots and yellowing. I was leaning towards magnesium toxiticy. My tap water is 250ppm and smells funny. I also don't drink it.

Mechanicalbuds said:

Nice pics. It took me awhile to find the damaged spots tho. Mainly because mine are similar but more damage. My 1 week veg clones have 1/16 - 1/8 round holes on middle aged leaves. Also dead spots and yellowing. I was leaning towards magnesium toxiticy. My tap water is 250ppm and smells funny. I also don't drink it.

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Sounds like my tap water, dont even like brushing my teeth with it

I think it can be from overwatering or long wet periods caused by poor drainage also. Too wet soil limits the manganese intake and thats why it only shows on the new growth, because manganese is immoble nutrient so plant can't suck it from older leaves. I migh't be wrong because almost all the sympthoms look like eachother but thats the most logical one for me. I gave them little longer dry period to recorver and started sub irrigating my pot instead of watering from top so I can eliminate all the mineral leach caused by possible runoff. And seems like there is no new deadspots since then.

There is couple of more recent shots:

You should switch to an RO system for your plants. If you don't think you should drink it it's probably not a good idea for your plant to?

I don't hear it mentioned with soil to often but bad water can affect the validity of your soil just like hydro.

shawnery said:

You should switch to an RO system for your plants. If you don't think you should drink it it's probably not a good idea for your plant to?

I don't hear it mentioned with soil to often but bad water can affect the validity of your soil just like hydro.

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I am using well water both for myself and the plant. So I don't think I have any problems with my water. RO water is still better since it won't have any heavy metals in it but its not something thats accesible for me right now.