I don't particularly find the need for them unless I have a dead spot in the tank or need it to use a Sponge/corner filter. They aren't neccessary unless you need it for these things. They really add very little, if any, oxygen to the water. More is added through the bubbles agitating the surface of the water. So if your filter agitates the water, unless you like the looks of it or something I wouldn't bother with them.