They generally cycle at 50 hz(Matching the mains frequency) which gives it 4,320,000 cycles a day or 1,576,800,000 per year. So, your pump has been working hard all year and done nearly 1.6 billion cycles and you can't be bothered spending 15 minutes to give it a little diaphragm change? How fair is that? No wonder they get noisy and annoyed at being underappreciated! :lol: