16 months was how long that sediment ran..........
2 years is a typical time frame it seems.
AFA redoes theirs on this same time frame.
ADA Ps also adds a lot of water column ferts initially.
It stands to reason, adding KNO3 etc, as I've argued for about 4 years now, is similar to adding the ADA PS.
Water column or the sediment.
Does not matter there.
Some find that sediment dosing is easier, no argument there.
But you still have to add CO2, and some fish food, traces etc as well during that time.......so you really are not getting away from labor/work etc in any significant way.
Adding sediment + water column (ADA, MS etc all do this a bit more or less, just they run things more lean in the water column, not sure why, perhaps fear or dogma or marketing/perception?) is what I've been doing, we all do to some extent.
If you add a longer term depot of nutrients, then it will have a limited life span and taper off over time. ADA As still does have some nutrients.............even 1-2-3 years later, just not as much as the first few months.
CEC sounds nice and plays some role, but it's not as significant I think as some believe and speculate. We have not seen that this is the real issue, rather, the water column nutrients likely are taken up before CEC is locking nutrients away and then root uptake is occuring.
Everything is coming in from the water column above.
Leaves will have ACCESS FIRST.
It's a good product(ADA AS).
I like it and still use it.
A DIY version is the delta clay we use.
Or the various threads supporting mineralized soil.
Pre washing/soaking for a couple of weeks leaches the NH4.
ADA AS has a few weeks worth of leaching of the NH4 out itself..........
So how do you add and remove when you have fish in the tank?
2ppm of NH4 is not a good idea for the fish.........
I've done it and the effects on fish where no pretty. I did large daily water changes and added zeolite(10 lbs!) to control the issue.
I'd not suggest doing much in the swap.
Get a trash can, run your filter on that and add the fish there for 2-3 weeks.
Break tank down entirely, clean , rescape and add new ADA AS.
A year is enough time to look at a design for many.
Up to you really.
If you do not wanna deal with it, Black Flourite is a good option.
Or you can do the spot enrichment methods:
Mud cubes(frozen MS), or clay balls of ADA AS, added under specific plants.