I would go with Amazonia II. Like Gerald said before, I read on plantedtank.net that here have been some complaints about it turning to mud or dust but all customers were fully refunded. You also get more for your money with Amazonia compared to flourite and Eco-complete. I have heard of people mixing pool sand with eco-complete and I have done this myself but never upgraded to better lighting so it was a waste. I would recommend getting lights first because you can always grow plants with crappy substrate and good lighting. It would be a waste to buy expensive substrate and not have good lighting.