Gravel vs Sand: Choosing a Substrate

Gravel gaps let debris fall through, which can rot if you never vacuum. Sand looks clean and suits corydoras and loaches that sift through it, but deep sand without circulation can pack and turn anaerobic in neglected corners.

For planted tanks, use a nutrient-rich substrate or cap soil with gravel if you know how to avoid stirring clouds. Rinse new substrate until water runs mostly clear before adding to the tank.

Depth of one to two inches is enough for most setups. Match substrate to the fish you plan to keep — sharp gravel hurts long-finned species and some bottom feeders.