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Bio balls are spheres consisting of tiny tubes that provide a large surface area on which water-filtering microbes can grow. They are typically used in fish tank and fish pond filters to transform potentially harmful ammonia into benign nitrates. Bio balls work best as wet-dry filters, with moving water passing over them. This allows more oxygen into the tubing, feeding the growth of the beneficial bacteria inside the balls.
Purchase several bio balls and a mesh bag for them at a pet supply store.
Place the bio balls in the stream of water running through your fish tank's filter. Although bio balls will catch some pieces of algae, they are not meant to be used as a physical filter. Installing them downstream of a filter membrane will help keep them from clogging.
Place the bio balls in a mesh bag to keep them together and keep large pieces of organic matter out. Hang the bag in the stream of water entering your fish tank or pond. Since bio balls work best in wet-dry conditions where water is passing over them yet they are not submerged, placing them this way will maximize the growth of healthy bacteria.
Avoid cleaning the bio balls. Scrubbing them or using cleaning solvents may kill the bacteria they use to purify the water. If they are clogged by organic matter, try to remove it by hand without scraping out the entire interior of the bio ball.
- fish tank image by Tammy Mobley from Fotolia.com