I'm also a big proponent of if you know your machine and what your doing by all means do your own end of year final cleaning. I for one will admit I do't have a clue as to how to check for this or make sure you do that when it comes to the nuances of the RO. But I do know that you cant rinse or clean it enough so I error on the side of clean clean clean. I RO a fellow producers sap because he got a simple to use hard to clean machine and so after the first year it was all fouled up and he bought new membranes and they are shot also.