The only reason i'm asking about the coconut fiber mat is because we use it where i work to grow sea grasses. It looks like it would be a great filter media and i can get it for free. Not that other pre filter media is expensive.
bottom line is you can use anything for a filter= a place for bacteria to grow. as long as it doesn't leech chemicals into the tank= okay. ls&lr will just house critters to self clean = better.
