Salt, George is correct. They typically have no use in the application of a pond aeration system. They are to collect any particulates that pass through the external filter.

The only problem we have had with maintaing them in the past is as George mentioned, cracked o-rings and possibly with them breaking when you remove them for the vane maintenance. If that happens, Bill Cody may carry the replacements. If not get back with me and I can help you there.