substrate for a very large aquarium
I am considering purchasing a very large aquarium (8 ft by 3ft by 2ft tall) to keep mostly tetras and other small fish. However, I wish to also keep plants in the aquarium. I have lots of experience with fish keeping and some with plants. However, i am getting back into the hobby after a very long forced absence. I would like to grown swords, some crypts, red and green stem plants and some carpet plants. I plan on keeping the water soft with a PH of about 6.6 and temp about 78.
I would like some substrate suggestions. I need a substrate that will last for years. I don't mean its fertilization, I can always add root tabs and liquid fertilizer. However, I cannot change substrate due to algae in it. So, I am leary of aqua soil type substrates like Amazonia, even version 2. I am considering eco-complete planted, but I have heard that carpet plants may have difficulty growing in it. I plan a substrate of about 4 inches. Money is not a problem. So what substrate would you advise?