Quote:
Originally Posted by VaughnH
Inert substrates, which are almost all substrates other than ADA Aquasoil, do not "wear out" and need replacing. Those substrates don't provide nutrients other than by virtue of their high CEC, where they get the nutrients from the water column or substrate fertilizing. So, there is no reason why they should "wear out". Some will lose their particle form over time, and might be desirable to replace for that reason, but not because they no longer supply nutrients.
|
Actually, soil substrates
do supply nutrients and they
do wear out in time, unless they are able to store the excess nutrients that are added in the form of food and/or nutrient dosing. Also, I've observed that after several years the original soil has become a dense, clay-like substance, which probably further reduces its CEC capability.
The carbon that was in the soil becomes exhausted in a year or two and (probably) doesn't get replenished.
Bill