Planted Tank Obsessed
Join Date: Dec 2010
Location: Northern VA, USA
I considered carbon because there is a known phenomenon in the terrestrial gardening world called "Terra Preta". Ancient Amazonians would create pits of charcoal and these pits would become literal oases amidst an otherwise nutrient deficient soil. The reason is that the amazon gets so much rain that all the organic material and nutrients wash away, but the areas with the charcoal sequester everything. If we are talking about CEC levels, nothing matches activated carbon. As already mentioned, if the carbon were allowed to absorb all the necessary nutrients through a soak, it would last indefinitely as a substrate.
I guess the other problem though is the price and also, as it seems others have already tried it, it is really lightweight.