The favorite diffusers around PB are the Vertex and Matala brands. They are mentioned more than the other styles anyhow. They are considered a membrane diffuser and require less maintenance than the stone or tube styles. You can install them and pretty much forget about them unless you are more ambitious, like me and a few others, and like to fiddle around the pond..then pulling them up once a year and cleaning the pond slime off the membrane would be recommended. I'm not sure this is really necessary and you risk breaking the plastic housing/fittings in the process. I bought my Vertex diffusers and weighted line form esshup (a post above) from his linked HoosierPondPros website.

After checking the temp difference between the bottom and top waters in the deep area, which would tell you if your pond is being turned over successfully, you still may choose to add aeration. If the small temp difference exists and additional aeration is not needed for turn-over, additional aeration could be added to aid in water surface conditioning on your end. This would help with any floating films that tend to develop in the lack of wind across the pond or during no-rain periods. These diffusers could be set much more shallow (2 to 3 feet from the surface) which will improve the surface turbulence, allow for more diffusers to be used with the same pump, and cover more water surface.

If you do NOT find that small temp difference, your pond needs more turnover and I would suggest putting at least one of your diffusers in the deepest water you have access to. This will aid in moving more of the deeper water to the top and, hence, the overall turnover of the pond.

Fish on!,
Noel