Make sure your lily pipe is just below the water surface, and It should be creating a Venturi effect, which will help to agitate the water .. I have the lily pipes and this is exactly what it should be doing.. Additionally you may wish to look at a surface skimmer... But I note the following.. Do not agitate the water too much as your Co2 absorption in the water is diminished, you need to resolve the reason for the scum on the water surface.. In order to have a balanced aquarium..