Reddit mentions of CANNA Coco Brick 40l Expandable Natural Plant Medium Soil Substrate, 40 Liter Expanded - 8 Liter Dry, Reusable (1)

Depends on whether you want bricks that you reconstitute yourself, or bags ready to use. Whatever you get, be sure it has been properly processed by the manufacturer or you will have issues.

My recommendations:

Coco Bricks

Ready to Use

If you go the brick route, you will also need to mix it with at least 30% perlite.

I have been growing for the last 4 years and I've learned a thing or two. I agree you shouldn't be switching up your soil regimen so frequently. Stick with soil or coco and roll with it (even if you fail a few times) the lesson will be learned.

I have grown in soil with success but the reason I'm writing this is to make you aware that I've tried growing in general hydroponics coco coir and it is terrible. The ph is not nearly as stable as this product by cannna https://www.amazon.com/gp/aw/d/B010OG1MVA/ref=mp_s_a_1_1?ie=UTF8&qid=1500811502&sr=8-1&pi=AC_SX236_SY340_QL65&keywords=canna+coco+coir&dpPl=1&dpID=418-8Gl8kBL&ref=plSrch it's very ph stable and I can even germinate in it. The general hydro coco not so much

this is what I use