Bio balls are small plastic balls mainly used as the biological media in wet/dry filters. These little plastic bio balls have lots of surface area for the growth of bacteria for filtration.
I use Bio Balls in my 150 gallon and my 200 gallon reef tank. I use them in the overflow to help increase oxygen level and as a bacteria bed.
I would never rely on Bio-Ball allone but I like to use them when there is enough room in the tank. More place for the bacteria to establish on and more oxygen can’t be bad.
Bio Balls are not always equal in terms of surface area, water retention and ability to bring oxygen to the water. I don’t know enough about the different brand available so if you know about that, feel free to use the comment box bellow and let us know.
My main problem with bio balls is the price. I just can’t understand why those little plastic ball cost so much.