Rust

rust Spots.. no yellowing Mainly old leaves at the bottom of the plant

done a little digging and some people are saying this is a type of mould..
Rather than a deficiency or nutrient blockout of some sort?

Doesn't look like rust fungus.

Whats your feed? Medium? (looks like coco) pH?

Can happen to leaves that touch the medium. Looks like you may have inadvertently got a little bit of water on the leaves. If you look close it looks like deposit on the leaf surface. Possibly just a victim of unintentional foliar feed probably. Maybe I'm wrong, who knows! Good luck buddy!

It’s in coco. Using canna coco a&b and all the other nutrients via there feed chat.. I’m using half the does specified
Ph around 6 I have a colour chart so it’s not the most accurate but I try me best. Woke up this morning to find it’s spreading on the plant and some of the upper leaves tips are turning brown now