Generally you should rebuild your pond aerator compressor unit every 3-5 years under normal conditions.  Air filters should be changed or cleaned once or twice a year. 

Pond Aeration Rebuild Kits & Filters

SRC Stratus Compressor Rebuild Kits Fits Gast
SRC Stratus Compressor Rebuild Kits Fits Gast
$65.59
Stratus SRC series "Gen 2" rocking piston compressors are specifically designed for the demanding job of 24 hour...
DC22, DC12, Repair Kits
DC22, DC12, Repair Kits
$75.29
DC22, DC12  Repair Kits If your air compressor runs but does not pump air after a couple years...
ERP Compressor Rebuild Kits for EasyPro Stratus Aerators
ERP Compressor Rebuild Kits for EasyPro Stratus Aerators
$57.99
ERP rocking piston compressors contain these wearable internal components. Like tires on your car, these parts need to...
Vane Repair Kits - RV33, RV75, RV100 Gast Compressors
Vane Repair Kits - RV33, RV75, RV100 Gast Compressors
$109.89
Gast Rotary Vane Compressos are long lasting and continuous duty compressors that hve less depth capabilities than the rocking...
SRC Stratus Compressor Rebuild Kits Fits Gast
SRC Stratus Compressor Rebuild Kits Fits Gast
$74.29
DC22, DC12, Repair Kits
DC22, DC12, Repair Kits
$79.39
ERP Compressor Rebuild Kits for EasyPro Stratus Aerators
ERP Compressor Rebuild Kits for EasyPro Stratus Aerators
$57.99
Vane Repair Kits - RV33, RV75, RV100 Gast Compressors
Vane Repair Kits - RV33, RV75, RV100 Gast Compressors
$109.89