If your aquarium will have live stock (fish, shrimp, ...); I would avoid potting soils. Also having used eco-complete it isn't much better than inert substrate. Some folks recommend a clay base (like t-sorb) to help with cec exchnage (which is what eco-complete helps with in theory). Also unless you are going hi-tech (using co2 injection) and have extremely demanding plants I would skip soil based substrates. Here are a couple of aquariums that have inert substrate:
Of course a lot depends on the specific type of plants you grow as some are more demanding than others; but you can in fact get decent plant growth without expensive substrate.
Of course a lot depends on the specific type of plants you grow as some are more demanding than others; but you can in fact get decent plant growth without expensive substrate.