laterite - any alternatives suitable


A question from a friend of mine in Southern Africa is currently setting up 
a planted aquarium (5'x2'x2') and has been able to purchase a suitable
heating cable. He wants to follow the recommendations of the Optimal
Aquarium (I sent him a copy), but Dupla equipment is not imported there,
due the exchange rate, as it would be to costly for 98% of the population.

He wants to add laterite to the gravel. He has contacted various universities,
geologists and metalurgists and all have said that no laterite is found in his
region, only further North in Mozambique and Tanzania. I was wondering,
in Sydney, various companies sell a product known as chelated iron 
(FeEDTA) and another called iron sulphate; could these be used in a suitable
mix with the lower section of the gravel to provide a fertile subrate that could
mimic the more common laterite/gravel substrate.

These products are commonly available for terrestrial gardeners and therefore
would be more commonly available in Southern Africa. 

Any comments on this would be greatly appreciated, has anyone tried a 
cocktail such as this?

Another question, would he be advised to just set up the tank without an
additive to the gravel (using say PMDD instead) and would the substrate 
heating still be as beneficial as with laterite?

Thanks in advance from my friend in Africa :-)

On another note:
To all that inquired about my pH controller experiments and pH electrode 
investigations, I hope to put a paper together in the near future, together
with graphs and photos for the Krib.

Marque Crozman  APD - ANGFA(NSW)