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 came in a paint bucket. Can anyone recommend me good substrates for a heavily planted tropical tank?