Hi there,
I set up my planted tank almost 3 months now. I used Dalton aquatic mix at bottom for 2.5cm deep and and another bag of flourite black 2~2.5cm on top of it(same reason, too pricy). The total depth of substrate is 4~5cm, same level of substrate at front and back.
My tank is 60cm*40cm*40cm. Here is the result.
hitech planted tank Benson C NZ by popo2424, on Flickr