Heres what I'm reading, Page 16 of the Manual - 6 months for a peristaltic pump head seems about right. Very similar to what other companies are recommending for replacement though usually its just the hose that needs to be changed out.
Cleaning and Maintenance
Poorly maintaining your ReefBot dramatically affects the test results.
In that regards, kindly make sure that any replaced part is compatible with the ReefBot, and as per the following best practices:
• Replace needle and syringe every 50 tests or whenever needed
• Replace the heads of all pumps:
• every six months, or
• at any sign of malfunctioning
• Clean the reaction and rinsing chamber every 100 tests or whenever needed by following the procedure below:
• Soak both chambers with warm (not hot) water for about two minutes
• Scrub firmly with tissue paper or a small brush
• Always check that RODI has 0 TDS or it will dramatically affect some tests, e.g Magnesium