[drcannabis.io]

Thanks for sharing our guide to potassium deficiency!

It does look like potassium to me as well. But there's something else going on, the yellowing in between the veins of the leaves indicates it.

Some of the fertilizers you mentioned are really strong. Most likely there's an imbalance of the soil pH, salt excess, nutrient lockout, or something related to the root system.

I'd start by finding out whats the pH, checking if the roots are OK, and flushing the soil in order to start feeding them from scratch.

GL!

 

[Creativepatron]

I agree with @Aqua Man Potassium def will show in the seration of the leaves, which is unique for K. If you look at the Mulder's chart and see if you might have locked out K with OSF maybe? I made the mistake of adding OSF right before flowering before and it seems to cause K def. If you were using coco coir, you would have Mg and Ca problems instead, but you are using peat right?

Yes peat. What is osf ??