The Cycle Stop Valve was introduced in 1993. So anyone in this business who hasn’t heard of them, probably doesn’t get out much. What’s worse are the ones who have heard of them, and either act like they haven’t or try to discredit them so they can sell you a larger tank and replace your pump more often. Just Google CSV or Cycle Stop Valves and you will find plenty to read. Yes you can always add a CSV later and you will need to. Because a 19 gallon tank only holds about 5 gallons of water and your pump will still cycle on and off a lot without a CSV.