Yes, I have been monitoring the pressure. No drop, yet.
Having a backup is a good idea for your business. I am just trying to mitigate the impacts of down time while rebuilding the compressor. If it is the middle of summer, then I probably need to work quickly.
We try to have rebuild kits for all the different compressors, but that still could mean 24 hours without aeration or longer. When the compressor stops, there could be a number of things why it stopped. Capacitor went bad, a power surge smoked it, just needs a rebuild or the cooling fan stopped and the compressor overheated, meaning bearings, etc. are toast. Sometimes it's quicker and less expensive to just buy a new compressor.
Don't forget to clean the diffusers once in a while. Mfg says once a year. I just replaced air stations in a customers pond that were a tube style, and they had split. There is no telling how long they were like that, he had never pulled them up to clean them since they were put back in the renovated pond 7 years ago.
If people are pushing the limits, and it's really hot out, there's no reason to take chances. I have had 3 phone calls this year by people that have had partial or what seems like complete fish kills in their pond.............