That's very interesting, thank you! Particularly the considerations on substrate for tiny plants, like Hemianthus callitrichoides
One question.. it seems the sand didn't cover all of the substrate, though then it was covered by the plants. Is the capping layer mostly to keep the soil down or does it have an specific purpose?
I'm not sure I'm going to be able to get gravel of 2-4mm :/
I can't wait to get the book.