Volcanit is original volcanic gravel to the aquarium, with Ph neutral. The pore structure of fine gravel, encourages bacterial activity that increases the biological nutrient removal in the gravel. The result is a magnificent plant growth. Volcanics is mixed with 10% of ferrolita, a fertilizer that ensures your iron absorption remain stable for a long time in the laterite. The black and red volcanic enhances the beauty of aquarium plants and the color of the fish.