If you maintain your chemistry properly, the results will speak for themselves. Crystal clear water. Your sand should perform in what would almost appears to be effortless fashion with the occasional backwash. Two things might cause concern in your sand filter over time though. The sand might become channeled in such a way that water feeds through the path of less resistance and just creates its own voids in the vessel. That's when a deep clean might come in handy. The other situation is if there is a mechanical failure such as a broken lateral, hub assembly, center pipe, etc. Then you would see sand spewing out of the return jets. Other than that, the sand should perform well.