Hello, everyone!

For a long time now I've had my axies on giant black river rocks but the tank is so tedious to clean that I've decided it's high time I switched to a different substrate. I was looking for some sort of black substrate that would be either digestible or fine enough to pass through their systems without causing impaction? Does anyone have any ideas on what I could use? I was thinking just some generic black aquarium sand from the pet shop but I'm kind of wary about it since the sizes of some pieces seem to exceed 1mm. I was wondering it maybe the exo-terra black desert sand might work? Or maybe even Marfied Controsoil which I'm pretty sure is digestible, but I'm not really well versed in the ways that it could alter the water chemistry.