Rust?

Can anyone tell me what this mite be ?

only on a few older leaves on one Plant at the moment apart from one speck on another plant.
Mould, deficiency, lockout?

We can't just simply guess.

How could we know if it's mold if you don't inform us of temperature and humidity? How would we know about lockout if you haven't stated what pH water you're using? How would we know about deficiency if you haven't stated what nutrients you're using and in what quantity?

Please, help us help you. Tell us about your grow.

Sorry I thought it mite just be a standard issue for the symptoms that was known just not by me..

So, temp 70-80
Humidity 40
Ph is roughly 6 but I have a colour chat not a pen so this can very unfortunately.
Growing in coco using canna a+b in half doses along with cannazym and rhizotonic both in half dosage

NL auto

Some newer leaves have some brown on there Leaf edges now

This: "Ph is roughly 6 but I have a colour chat not a pen so this can very unfortunately." To be successful in coco, you'll need to learn to manage your pH. In coco, 5.8 is the sweet spot, if it varies, it should only vary a couple tenths either way. If you don't manage your pH you'll continue having these issues. Dial in your pH firstly before you do anything else. Good luck.