Wy Renegade
Aquarium Advice Addict
You won't have any issues with the size of the substrate. My only concern was the cost. I run all my mbuna tanks with regular aquarium gravel and have for 20+ years without issues. If you look at pictures of the lake substrate where these fish originate from, it is every size for sand to gigantic boulders. I guarantee you the fish don't have a preference. People may, but the fish don't. In 20+ years I've never yet had a single fish of the hundreds I've kept, bred, and raised from fry tell me that they prefer sand over gravel .