I've run 100% Hempys for a few years.Perpetually with different strain. Sucessfully even. I still run solo cup hempys,now with calcinined clay added.I've also ran coco and perlite hempys using coco loco.Good runs also.
The thing with all perlite hempys is they run like a well oiled machine and will grow trees,even in small containers,until they don't.Might be an environmental shift,ph,or just that one particular cultivar doesn't like it's conditions.When everything else environment,feed ph etc. is "dialed" in and you still have issues,Media/Medium is usally the culprit IME and opinion in regards to all perlite hempys.
Perlite doesn't have good CEC or cation exchange capacity or an ideal water retention retention ability.However it does wick execeptional well and has a unique water holding ability.
Possibly why Hempy himself decided to run vermaculite in his final mix.
Perlites water retaining ability isn't ideal but the res under the hole and it's wicking ability.is what this is for.I've never run a verm+perlite hempy.Don't care for the messy vermaculite.Clacinined Clay(Turface) is my substitute for vermaculite.
Coarse perlite, the horticultural grade we use doesn't absorb as much water as finer particles so it'lll help to mix some in.Also you must wash perlite thoroughly.Perlite dust sludge will have you chasing your tail an dreaded PH ghost. In 100% perlite hempys,PH issues can or remedied quickly as the product is inert
I feel ph is supposed to swing in any and all media. 5.8-6.3 I've found is a nice range.Meaning,if making your nutes to hand water, don't keep adjusting the solution to be exact. The next watering when made, adjust up or down. I just feel and have seen the drift allows for certain elements to be absorbed throughout a range.
I have since moved away from flowering in 100% perlite hempys.I still use my hempy mix in my flowering girls system(PPK). I have a veg tent full of healthy hempy solo cups seedlings and clones. But they have the mix of the turface and perlite.
This isn't a knock on perlite.Just some thoughts and my own personal experiences with it to help understand it.Once I understood the media/medium? My hempy runs were pretty flawless.
Maxibloom was my base nute at the time.I tried others,but maxibloom was what fit my environment,grow style,and the girls seemd to prefer it over the others I tried at the time.