Blue Biochemical Cotton 50 × 30 × 4CM

specifically a blue biochemical cotton pad. These pads are typically used in aquarium filters to help maintain water quality by providing mechanical and biological filtration.

Here are a few common uses and benefits of biochemical cotton pads in aquariums:

1. Mechanical Filtration: The pad helps trap debris, uneaten food, and other particles from the water, keeping it clear.
2. Biological Filtration: Beneficial bacteria can colonize the surface of the pad, helping to break down ammonia and nitrite, which are harmful to fish.
3. Versatility: The pad can be cut to size and used in different types of filters, such as hang-on-back filters, canister filters, or internal filters.