I'd like to get an air stone, to increase the surface agitation in my tank and get rid of the filmy layer that is always there. I have a very small freshwater tank-1.5 gal- and I'd like to know what kind of air stone is best to get. I don't have much space in the tank, and I don't have room for more equipment with tubing or wires. I already have a filter/bubbler, but it doesn't take care of the problem. Is there an air stone or something like it that will release bubbles to the surface? Anybody have an idea? Thanks.