Give Your Tank a Dramatic Look with Pewter Black Substrate Pebble Size: 6-8mm Dark Black Coloration When Wet Minimal Effect on Water Chemistry Pewter Black gravel is a stunning substrate that exhibits a nearly jet-black color when wet. It can be used as a cap layer for a planted ...Give Your Tank a Dramatic Look with Pewter Black Substrate Pebble Size: 6-8mm Dark Black Coloration When Wet Minimal Effect on Water Chemistry Pewter Black gravel is a stunning substrate that exhibits a nearly jet-black color when wet. It can be used as a cap layer for a planted tank or simply used by itself if you're not using a separate plant-specific substrate.
The 6-8mm pebble size allows for a massive amount of surface area for the colonization of beneficial bacteria.