growing in bat mix- overfertilization or deficiency

Hi all
im growing delahaze, sensi star and icecream in bat mix/plagron ...the growth was beautifull during the whole veg stage.They're already in 5th flowering week.I havent been feeding them for about first 8 weeks as i heard stories that bat mix is a realy strong soil.But after they were switched to flowering small signs of yellowing appeared.I added some biobizz bio bloom , just a tiny bit but there is no improvement, rather more signs of yellowing ... from the bottom... fan leaves turn yellow, with dark patches... and I've also noticed small black spots on top leaves that turn yellow slowly....so i know that it might be a potassium deficiency ...schould i give them more nutrients? I really dont want to burn them with that plagron soil....I would appreciate any advice
I measure ph of water regulary , humidity 40-60%, temp.22-25%....

The leaves will turn color and die off during flowering. The plant uses stored nutrients as it focuses on flower formation and ripens. I would not add anything. Just water. If everything else looks good I would just wait it out.

Cannabis is an annual plant. It only lives for one season, then it dies. All flowering plants will eventually die and I am guessing what you are seeing is the plant nearing the end of the cycle.

The only problem you see is that im afraid that the flowers would be affected leafs curled down and up with dark patches. i think im gonna give it a try and feed them more one more time.i honestly doubt that my pot with bat mix would be enough for plant during whole life cycle.... thank you for an advice )

Apologies for pulling out such an old thread.

We've had the same problems with Bat Mix. First we thought it was a lack of N but adding N only gave us weird overfertilizing issues like strangely shaped leaves, foxtailing or a growth of small leaves around the buds which made manicuring a very long job.
We will try CalMag next to see if that makes a difference but at the end of the day the end product was always fine even with the early yellowing of the (big) leaves. The buds don't seem to mind this and the little leaves around the buds are usually nice and green.
If CalMag doesn't make a difference we will just carry on as we did, just water and a little bloom ferts between week 4 and 6 in of 12/12.