You're doing the right things buffered coco is the way to go much less chance of problems down the road.
Dude im in Australia as well, we get plenty of premium coco products here. You just have to go to a hydroponics store... not bunnings, or you can also find a lot online. I would recommend nutrifields premixed pre buffered 70/30 coco/perlite mix , or if you want a heavier perlite ratio, get some canna coco pro+ and then mix in some perlite to your desired ratio, but remember the more perlite the more often youll have to feed, possibly mutiple times a day in flower. Depending on size of pots and the plants themselves. Sent from my SM-G960F using Tapatalk
I only use bloom nutrients from seed and don't go to low on the ph. I never get cal mag problems ever. I heard even canna coco can come high in sodium. I get excellent results with cheap coco and perlite. Only one in every 20 bagseeds planted would complain, with a few rust spots.
Hey mate I ended up deciding making my own coco/perlite mix. Went 70/30 coco/perlite. Just finished hydrating the coco and started buffering it. Currently building a automated feeding system cause I’m not home to feed multiple times a day.