substrate ideas

What are the uses of afragog in an aquarium beyond having a large surface area for bacteria? I remember reading it last time and deciding to add it to my tank; however, now I can not find any information about it. Is there anyone else that uses it in their aquariums/filters?

Hi, I have just got a 200l tank and I'm not sure what substrate to use. Some people say hydroton clay balls are best but others say the Seachem Fluorite is best. The tank I got comes with a ton of gravel which I would love to use but I'm not sure if it's good? I dont know the name of it as it...

This is my 29 gal long tank, I really want to switch the substrate to sand for my cories and khuli loaches, what would be best and look best? These are the fish I have: - two neon tetras - two angelfish (one silver with black stripes and one koi) - three corydoras - two khuli loaches - three...