Assuming no other complaints you would only need to change water to lower the total dissolved solids level or cyanuric acid level. TDS should be below 500ppm and cyanuric acid ~50 ppm.
weekly
According to my dealer, it should be changed at 150,000 km.
Passwords should be changed every month.
weekly
When its old
When it is dirty.
When it is dirty.
Bass strings should be changed every 3-6 months, depending on how often you play and the sound quality you desire.
The Aprilaire filter should be changed every 6 to 12 months for optimal performance.
30000 miles
If you do not drive it often, I would recommend getting it changed every 3 months. That is what many mechanics tell you to do.
The engine oil should be changed every 3000-5000 miles