If your Dosing ferts in excess it should recharge, it all depends if the granules break down into smaller granules/dust then the flow around them will be reduced which will affect the CEC as it will be effectively clogged up
I should imagine it behaves like any other soil, in that it depends on what you cap it with, whether you water column dose etc. I haven't used it in an aquarium so I can't say for sure.
But if it's just used as a growing medium in conjunction with additional water column dosing, and capped with fine gravel about 2-3mm it should last almost indefinitely.
When you start with something like <"Akadama"> or <"sphagnum peat">, all the cation exchange sites are initially filled with a proton (H+ ion), because they have formed under conditions of high rainfall. These will then be exchanged for more strongly bound multivalent cations from solution (your tank water).
If you start with a "blank slate" substrate you can load it with cations by soaking it in a strong solution of ions, I assume this what ADA do when they make <"ADA Amazonia">.
The first time I used the moler clay "Tesco Cat Litter" I rinsed it in our tap water (hard about 18dGH/dKH). It didn't get rid of the smell, and it meant that all the exchange sites were filled with Ca++ and HCO3- ions, so it raised the pH and hardness of the <"rain-water tanks I used it in">.
If I'd used it in a tank with our hard tap water, it wouldn't have had any additional effect effect, because the ion exchange sites would already have been in equilibrium with the water.
The next time I prepared cat litter I just left it outside in the rain for ~ six months. I could have soaked it in an acid solution (acids are defined as "H+ ion donors"), but I would also have added anion.
If I try it again I might have a go with hydrochloric acid (HCl) first, followed by some time (couple of weeks?) in the rain and see what happens then.
Never thought about that but it makes sense the sites for exchange get blocked with ions that have higher ionic bonding than the ferts ions, so if your water is hard enough I suppose your AS could end up being similar to an inert substrates.
So WC dosing is more important in older tanks with AS
Another nail in the coffin for hard water and a good point why soft water and growing plants makes sense!
The only way of getting the substrate to release the ions it has bound would be to put it in a strong solution of another ion. If you have a high enough concentration of ions in solution the differential between the substrate and water will mean that a less strongly bound ion (like sodium Na+) can replace a more strongly bound ion (like Ca++).
This is why you can re-charge ion exchange resins for water softeners etc in a strong brine solution. Via <"Wikipedia">
Water softeners are usually regenerated with brine containing 10% sodium chloride. Aside from the soluble chloride salts of divalent cations removed from the softened water, softener regeneration wastewater contains the unused 50 – 70% of the sodium chloride regeneration flushing brine required to reverse ion-exchange resin equilibria.
Hi all, All active substrates will stop being "active" after a while. They don't lose the ability to exchange cations, they've just reached an equilibrium point with the tank water.That is the real point CEC is "Cation Exchange Capacity" and that is exactly what it is, the <"ability to retain and exchange cations">.