Nutrifield coco mega brick+ jacks 3-2-1?

I picked up a nutrifield coco mega brick that I will be using jacks 3-2-1 with. My question is should I rinse since it’s supposed to be pre buffered or just charge it with the jacks and go with it? Also what mix of jacks would be recommend to charge this coco? Maybe extra cal mag?

I believe most coco is pre washed, buffered and ready to use but it doesn't do any harm to test the ec and give a soak in calmag.

I would hydrate with 6.0 PH 300PPM Jacks, wait a couple hours and run more of the same through it until runoff says 300PPM. Drop a seed.
Concerned about the buffering? Hydrate with calcium nitrate/water, wait 24 hours, flush with 300PPM Jacks until runoff matches input. Drop a seed.
I use Canna Bricks, I hydrate n' go.
Put the calmag away somewhere you won't see it.