Article at Aqua Journal Online:
nature aquarium notes 01, How to use Aqua Soil.
The most interesting thing here is that ADA claims Aqua Soil can hold PO4.
I know it is a result of CEC of clays in raw soil + organic acids (fumic by article).
It explanes WHY in Amano's Tanks with Aqua Soil PO4 levels always below 0.1-0.05ppm. No limiting plants growth, but you have much less algae
in case of disbalance. This allows to fix things
before tank turnes into desaster.
This is also explanes how substrates with high organic content (as eathworm castings or aqua soil) can be a
long term source of nutrients (including PO4!) for plants.
DIY will work just fine:
high CEC substrate (calcined clay as Profile, Turface...) or Zeolite + earthworm castings at the bottom + micro - FTE as JBL Florapol + some peat + bacteria culture starter.
Kudos for ADA.
Their entire System is greatly different from all the rest, and is unbeatable for Stability and Usability.
Reading:
Mechanism of phosphate fixation is over here -
Topics in Fertilization and Plant Nutrition, SEVEN LECTURES ON IRRIGATION", By Prof. Uzi Kafkafi.
More on phosphate fixation
- Substrate Ideas, Jim Kelly, Oct. 1998.
Organics makes a large share of CEC in natural water's sediments: see
Relationship between Fumic Acid and the Force of Ion Exchange Adsorption of River Sediment.; Koizumi Sadayuki, Takayama Katsumi, 1999.
Tons of links on the subject in texts and at the very BOTTOM of this page (in russian) - замена Aqua Soil -> фиксация фосфата. 