HELP! I am looking for help or information! I am in the process of updating/restoring my home, it has 4" round galvanized downspout. I need a downspout diverter to fit 4" downspout. I need a diverter to install on the downspout so I can switch when cistern is full to downspout that runs out to yard. Any information you can provide is appreciated. Thank you very much for whatever help you can provide John Keylor