Oh sure, Xuan. That sounds like a great idea! I often use a thin layer of charcoal in the bottom of my shallowest pots. I really think it helps to keep the soil fresh when there is a high PWT:container height ratio. I will say though, that given the ingredients you're using, size of the particles will be important. How fine can you grind the pieces? What else is available to you there for inclusion in the soil?

If you have a way to grind the hard part of the shells, there's no reason you can't use that portion, too.

What a great example of innovation. I love it! I hope you come back often & keep us informed as to how you're efforts are paying off? ;o)

Al

Xuan - let me know when your daughter will be in the States on business, and I'll gladly send you some more perlite! I wish I could get more than one bag in a package for you... it's light, but bulky.

Hi
That is among my favorite mixes for tropicals. n warm humid climates it will last at least 3 times longer than any type of bark. I love it for semi terrst. orchids.
You also might try ground lava stone with a handfull of peat. You can use it again and again.
i would use nothing else but here it's far more expensive than bark and I'm WAY to lazy to make my own .lol
What are you trying to grow?? gary