Best Seller | Bio-Substrate Midnight Pearl, 5 lbs., Small, Black All Aqua Natural gravel and substrates are 100% natural, sustainably sourced, triple washed and kiln dried. Our high quality products create natural beauty combined with large surface areas for beneficial bacteria colonies and easy cleaning. This pack... ... more Bio-Substrate Midnight Pearl, 5 lbs., Small, Black All Aqua Natural gravel and substrates are 100% natural, sustainably sourced, triple washed and kiln dried. Our high quality products create natural beauty combined with large surface areas for beneficial bacteria colonies and easy cleaning. This pack... Petco.com | | $15.99 go to store |