Rust fungus or Ca/Mg disorder? All plants are being affected

[Vancho]

Hello everyone. I've got 7 autoflower plants from BSF seeds. Passing day 40 from opening and the last week i noticed those brown spots from probably a rust fungus or a lack of micro nutrients? I gave them all a fungicide against rust, oidium and other leaf spot, but brown spots kept appearing and in other plants too (ATM four ill plants and 1 is outside the grow room to avoid spread). I'm from Buenos Aires, Argentina. The indoor is 1.5m2 with 900w of COB led full spectrum + white. Using a mix of soil, compost, peat and vermiculite. Using the Top Crop set for fertilizing (brand from Spain). Indoor temperatures fluctuates around 25-28°C with good ventilation.

 

[Mañ'O'Green]

@Vancho Welcome to AFN.

What is the source and EC of your water? What feed schedule are you following? What is the EC of your fertilizer?