Maintain a healthy aquarium with the Aqua One Vac A Tank Gravel Cleaner 23 to 40cm. This cleaner will remove waste material from gravel while leaving the gravel in place. This reduces the build-up of harmful chemicals such as ammonia and nitrate so your fish are kept healthy and happy. Aqua One Vac A Tank Gravel Cleaner us designed for easy use. With less mess, less effort, you will love this time saving aquarium accessory.