Just an Idea

I've been reading these posts about laterite and ways of introducing iron 
to the plants.  These us just an idea, no idea if it would work.

Along with plants I'm interested in Reef aquaria also.  Friend of mine 
jsut set up his reef tank using this substrate method which optimizes the 
biological filter.

It consists of multiple layers of different material.
The bottom of the tank is empty, he placed empty cassette case on the 
glass floor, on top of that he added egg crate, also known as light 
diffusers for flourescent lights.   On top of that he add a layer of 
screen door screen.  Then a layer of crushed coral, then two layers of 
nylon screen, then a layer of finely crushed coral.

What does this mean for plants...well.. How about the same thing with 
different substrate.

Use the light diffusers, first layer of screen, then a layer of laterite, 
then a screen, or a layer of thick pebble/gravel, then several inches of 
fine sand or small gravel.  

My thought would be to run tubing down underneath the light diffusers to 
force warm water or just a power head.   The water from this would be 
from a sump.  In the sump you could either just add your fertilizer drops 
or how about a laterite bed that you could replenish.  Use light 
diffusers to make several layers and have water that would flow through a 
bed of laterite that can easily be removed and replaced.  The water 
(hopefully rich in iron) is pumped underneath the substrate and into the 
laterite there.

Just a thought.  THere are a lot of modifications that could be made but 
I thought the idea might work.