I've recently bought a LOT of eco-complete for a 200 gallon tank I'm
setting up. I had been under the impression that I could use the
eco-complete as the only substrate in the tank, but I've recently read
in a book on the subject that I should use a "nutrient rich" substrate
(like laterite) as only a thin layer in a multi-layer substrate. Does
anyone have any experience with Eco-complete. Can I use it as the only
layer or do I need to provide multiple layers of different types of
substrate to properly house my aquatic plants?

Not sure if it matters but here are the specs on the tank so far:

200 gallons (approximately)
4x96watt 6700K lighting
CO2 injector should be arriving soon
2xRena XP3 filters
2x400 watt submersible heaters

If anyone has any advice or suggestions, I would be greatly
appreciative. I really want to get this tank right on the first try!

Best Regards,
Kevin