Is this something?

[TerpyTyrone]

 

[Texagonian]

Not that much biochar. More like a crushed lava1, perlite 1.5, biochar .5. Perlite is cheap, so it makes up a fair bit of it.
For extra Biochar I use the ac from my old filters, let it sit for week in a fish emulsion or similar solution. Add to the soil. Reuse and no waste. Lol

Bio char is the shiz man for colonizing beneficial fungi and microbes. I’m gonna have to use this idea. You had a comment in here somewhere about repacking the filters with coir carbon right? Where could a guy get that. I wanna add some to my compost tumbler. It’s the missing ingredient!

 

[Erick31876]

GRANULAR Activated Charcoal (Coconut) 4x8 mesh

<div class="product attribute description">Granular Activated Charcoal (GAC) 4x8 Mesh made from coconut shell. This hard, highly adsorptive charcoal is used primarily in air and vapor filters for eliminating odors and toxic vapors.</div> <div class="product attribute description"> </div> <div...

www.buyactivatedcharcoal.com

I bought the 55# box of it for $100 at a discount.
Have built my own filters and just refill as needed. Will last me years and years. Just keep it sealed up good. Built a few filters for some other growmies too, still have an 18 gal tote full. Lol.
For soil additive soak it in a bacterial nutrient solution for a week to colonize it prior to adding to mix.

What bacterial nutrients do you recommend to soak it in @Jesselikes2grow

 

[Texagonian]

A fish emulsion works really well, or ewc, compost and manure too.
For an outdoor garden, can use other things that get added to the soil as well.
Add fungal wood chips, household compost, (especially milk, fish, and bones) leafy compost, grey water, worm tea, fish tank water, you name it. Try to get the charcoal juiced up with calcium, nitrogen, bacteria and fungus before you put it into your garden.

Let it sit in the tea for about a week.

I’m digging it!