The only problem with coco is the grower which includes myself . I've done coco for a few years now and when I have had a problem it's always been my lazy ass not checkin PH or something stupid but my dialed coco grows are something of beauty like alot of others here . I take the blame 100% when I fuck up
I agree with Sun, all the coco issues I've had (apart from Fungus Gnats) was MY fault.
I really don't think there is crap coco, only untreated coco. I used canna bagged coco for a couple of years, superb stuff but expensive.
I switched to Hercules Neopeat brand cheap bricks, everybit as good as Canna I have found, I expand them with hot water then test the runoff (not had one yet that needing flushing, luckily) and then pre-charge with ec1.0 nutes and use.
I have used other cheap bricks that did need a flush, just stick it in a big pot with holes and run water through it till the runoff is below ec 8.8 then pre-charge with nutes and it's good to go.
The only downside to cheap coco is some of it needs flushing of salt, this will be the stuff grown by the sea.
All Canna do is steam tree their coco to remove salts then innoculate it with Trichoderma Harzanium fungus and bag it for sale.
I prefer to do this myself with hot water and mychorrizae and other beneficial funghi.