Reeflowers Iceland Sorrel Lavais 100% natural sand. It consists of lava rocks. Thanks to the microchannels and pores inside, it provides fertile areas for bacteria that provide a nitrogen cycle. It contributes significantly to biological filtration and helps keep the aquarium clean and clear. It does not affect the pH and GH value of the water and does not oscillate. It is suitable for use in all types of freshwater aquariums. It provides strengthening and development of plant roots. Available in 2 grain sizes : 1mm-3mm and 4mm-6mm