Calcium deficiency, nute burn or root issue

[OceanicBud]

Thoughts on these rust spots on outside edges increasing to the tip ends that curl once rusted?

Week 4 of flower almost done.

Full system spec found in my signature link under current grow.

Not exceeding EC of 2.0 for nutrients.

Only apparent on the fan leaves, sugar leaves developing look fine.

Environment dialled in at comfortable 23 - 27 degrees (73-80f) and water temp constant 19-20 (66-68f) with 50% RH

Could it be calcium deficiency, possible nutrient burn or a root issue?

I doubt LED light issue as it's happening on side and some lower leaves away from light. Nor will it be heat stress with A/C controlled temps.

Any guidance appreciated

OB

 

[Green thumb lou]

Can we see a pic please haha

 

[OceanicBud]

Can we see a pic please haha

It was there, attached once again!

 

[Green thumb lou]

This is what the bible says. But that’s just a possibility

 

[OceanicBud]

This is what the bible says. But that’s just a possibility

Well there we have it, it does look like K (Potassium) early stage deficiency, I did have this deficiency early on and a swift successful repair with some Nitro-K added, however I was always led to believe for some reason that this, as an additive to regular base nutrients is really only required in Veg stage (Not flower) Even the Nitro-K bottle says use through Veg cycle.

I'll add some and hopefully see this subside. Not a major issue yet, just want to get on top of it early, as to not harm the upcoming yields.

OB