Gravel White is CO2-resistant and water-neutral, i.e. it has no effect on water values and does not colour the water. Thanks to its size of 1 to 3 mm, it allows plants to take root in an optimal way. Because it is round, the natural gravel is also suitable for bottom fish such as corydoras. sera Gravel White has been tested by an independent institute in accordance with DIN 38415-6 / EN ISO 15088 and has been found to be free from harmful substances and is therefore suitable for keeping and breeding sensitive animals.