Hello! I have been reading the information on the debate between changing the sand in a filter and wanted to know if our pool and filter is 5 years old with being the original owners is it better to deep clean and keep the sand or should we change the sand? Also is it worth to add some DE to our sand no matter what process we choose? Any help is greatly appreciated! This is our first year NOT using the pool store that we have and doing this the TFP way! Very excited to get started!