Interpet Betta Gravel creates a fun interactive environment for bettas and is a great alternative to hard gravel! You can watch your betta play in and around the soft, lightweight balls which provide the mental stimulation they need to thrive. The Betta Gravel also adds beneficial bacteria and enzymes to the aquarium water which helps keep the environment balanced and healthy, resulting in clearer water. For optimal results, replace the gravel monthly and remove uneaten food to help replenish the beneficial bacteria and maintain clear water. If soft gravel shrinks prematurely, this is a quick indicator that the water hardness is not optimal for your betta.