On a recent trip I watched a few people use a pre-filter on their hose which fills the fresh water tank. Being a backpacker, we clean our filter before storing to keep any growth from happening. The Shurflo filters something like 650 gallons. If you do not use all 650 gallons, is it saf to continue using the same filter the next season? Any suggestions for drying or flushing the filter to be able to continue use the next season?