Hi I'm looking for a black bottom dweller safe substrate, preferably something like sand. I've considered seachem black flourite before but there's been conflicting opinions on it. Some people say it works well for even their bottom dwellers with sensitive bellies but other say it has damaged or worn down some part of their fishes. Anyone got any suggestions as to what I could use? I've been considering Dennerle crystal quartz gravel black as well but I'm not sure if waste will get stuck in between the granules?