I think you guys are mis-understanding my suggestion - it's not a diss on this grow or anything, I'm saying the fastest way to healthy plants is start new seeds or clones in a different medium. If the medium is too heavy you can try changing nutes all day long and they'll just keep dying, which is what's happening.
this stuff happens to me all the time, every year I experiment with something and have to kill everything. Finding soil mix that works right can be like wandering the wilderness for years, you head off in one direction and it takes a while to realize it was the wrong way.
I've seen a few friends struggling with it this year, they all found success by using a store-bought complete mix like Roots Organic 707 or Michigan M3 blend. THese are only available in the US though. It has to be a mix specifically designed for cannabis - this herb needs way more aeration and porosity than typical gardening plants and vegetables.
I can clearly remember my first grow in 2000 - I killed off $300 worth of premium seeds from Brothers Grimm - C99 - and Sensi Star from Paradise Seeds. I planted in some expensive organic potting soil, a local product called Coast of Maine Bar Harbor. It has premium ingredients alright, but it's heavy and thick as swamp mud. It's suited for outdoor raised vegetable beds, not cannabis in containers, way too high in compost and aged bark and only 5% perlite instead of 30% cannabis needs.