A good rule of thumb to keep the air compressor filter clean is to check on it every six months. Clean it if needed with high pressure air hose or simple replace it once a year.
Think of the filter as the same in your car, actually it is pretty much the same, filtering out small particles from the air before they reach the engine creating wear and over time damage the engine.
Is there loss of performance with dirty air cleaner? You bet, just like in a car or tractor the air cleaner has a job to do. Whether it’s a car, tractor or truck the air cleaner is working whenever the engine is running. When the engine is not running then the air cleaner is not working, yes same with the aeration system to but the aeration system is running 24/7. Our vehicles don’t usually run that long.
When the filter on the vehicle starts to get dirtied up or plugged up the engine will start to run a little less efficient, The dirtier the filter get the worse the engine efficiency is, sort of like partially closing the choke starving the engine for air, using more fuel.
Same thing with the pond aerator but we are not using more fuel, it is more of a restriction of air flow the compressor and down out to the diffusers, restricted air flow can also cause more heat to build up in the compressor too.
If the filter element is not too dirty it could be blown out, same with the shallow water systems and re-installed but if the filter is dirty and cannot be cleaned it should be changed to keep your compressor safe and providing enough air the pond needs.