[Michael]

What is the purpose of the peat granules and the horticultural carbon?

I've never heard of azomite, but I can see why you would add it for micronutrients.

 

[Michael]

My guess is that you could cut the potassium component (muriate of potash) way down, less than 1%. This is an intuition based on the amounts used in most MTS mixes.

 

[Michael]

I have heard of coir being used in aquarium substrate, but do not know how it performed.