Clay as sub-substrate?

Hi all
As the time comes nearer:bigsmile: when I'm allowed to get my new tank a few questions before.
I would like to bring more stucture into the ground. At the moment I just have the sand on the one side a bit higher than on the other but its not enough.
I thought i would use the clay (KAILIN?)from my pond-lining to modell a scape in the tank. Than I planed to put what ever sand i choose over it.
Ever anybody tried something like that, has done what experience or can somebody think of a reason i it might not work!
Also hope that i can lift the GH with the clay a bit.
The tank should again be a planted tank with mainly South American fish.
Thanks for your input

 

Try and get red latterite clay - they use it to form the base of roads. Its high in iron and the plants will love you for it