Pond Logic SilentAir RP Series Compressor Air Filter - Pre-2009 is a product listed under the Pond Logic brand. Air Filter Element Only. Airmax Aeration System Purchased Prior to 2009. Replace Filter Element Once Every 3 to 6 Months Specifications and pricing on this page reflect the data published by the source retailer at the most recent catalog refresh. Verify the current listing on the retailer page before purchase.