What is going on here? Rusty leaves

[Panico]

Hi guys and girls! Newbie here!
Medium is all purpose organic with peat and pomice, under a Marshydro FC3000 80% at about 50cm. 26ºC, 65%RH (actually 70/80 last week beacause of heavy rain). Currently flushing with pHd tap water taking care of a small N tox. This is happening in both Green Gelato girls, the other Northern Light I got in the tent is looking fine (all autos). Found out that these 2 plants have a shit ton of springtails in the medium while the healthy one have none...
I'm really loosing my mind on this...

P.s. one has less "rust" but leaves are curling like a blunt while the other is not curling but has way more brown leaves

 

[steamroller]

First 2 pics look likes a calcium def.

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[Panico]

First 2 pics look likes a calcium def.

Cannabis Leaf Symptoms Quick Guide With Pics | DRCANNABIS.IO

Use cannabis leaf symptoms pictures to quickly diagnose your marijuana plants. Find the pictures that resemble your plants and learn how to fix the problem!

drcannabis.io

Thank you for your reply!
I use tap water, Culligan states that it has about 56mg/L of Ca and about 16mg/L of Mg. I thought It was enough for not needing CalMag...

 

[Stonerbudz]

Thank you for your reply!
I use tap water, Culligan states that it has about 56mg/L of Ca and about 16mg/L of Mg. I thought It was enough for not needing CalMag...

Nope you should add some forsure