Corydoras barbels are very fragile, I'd find a better substrate. What consistency is Eco-Complete? I've never used it, but I've heard it's good for growing plants.
I just use regular TOP SOIL from the hardware store as the first 2-3 inches of substrate, plant the plants and cover it in pea gravel or large round rocks to keep the soil down out of the water.
EDIT:: This is what I get for not reading the last page of the thread before posting.