Absorbing Substrates

[Brian]

What substrates have the capacity of absorbs water nutrients and re-fertilize itself? (ionic exchange). The eco complete have this effect? I hear of substrates that absorb water nutrients and help to control algae, water discoloration and make the water more clean, This is real or only a mith?

[John N.]

Eco complete has a high Cation Exchange Capacity (CEC), which is basically the ability for a substrate to take nutrients out of the water column and supply them to plant roots. Like Tropica substrates, Seachem Flourite and ADA Aquasoil, Eco Complete can absorb nutrients to an extent and do exactly that. If you look at the grains of Eco complete you'll find that it is very porous, which is a characteristic of being a high CEC substrate. Eco Complete will raise KH and GH, and is said to have the essential micro elements.

Some substrates absorb water column nutrients better than most. ADA Aquasoil is known/suspected to provide an abundance of nutrients while lowering pH and KH. Since it's a clay mixture it's going to be better than Eco Complete when it comes to CEC.

I've never heard of substrates specifically controlling algae or cleaning water. But I suspect the overall components of having a rich substrate helps grows healthy aquatic plants which typically leads to less algae and a cleaner water in an aquarium. The tinting of the water could also help contribute to less light being available to algae (but also to plants).

In terms of water discoloration, Eco Complete will not discolor the water. ADA Aquasoil Amazonia will in the beginning, but will taper off with waterchanges. ADA Aquasoil Amazonia II is designed so it won't discolor.

-John N.