The Hydor Sintered Quartz Bio-Rings, 450 grams, are an ideal substrate for biological filtration. High surface area and the macroporous structure of the rings facilitates efficient growth of colonies of beneficial bacteria, both aerobic and anaerobic. Bio-Rings do not release phosphates or heavy metals and do not effect pH of the aquarium. For freshwater or saltwater aquariums.
You can use Hydor Sintered Quartz Bio-Rings as a replacement media for your Hydor Professional Aquarium External Filter or with any other filter.