Can you talk a little more about your choice of substrate and reasons for it?
For my low-tech 50, I'm still undecided between using just Eco-Complete substrate or put it on top of a layer of potting soil or something else.
If you're asking me, I'm going with the Turface for four reasons basically: it's almost completely inert, it's got a small grain size, it comes in the color I wanted, and it's cheap. I got my bag for $13 for 50lbs. Same amount of Flourite Red would have been over $50 and I can get the same or higher level of iron concentration in the substrate by using laterite on the bottom.